Hey there, this is not a guide made by me, in fact this is a guide made by Relic themselves. However it seems like it was lost in time, and one other user was able to find and show me this guide only trough "Way back machine".

It feels like it should have been available in the "Documents" folder in Impossible Creatures (IC) game files:
"\steamapps\common\Impossible Creatures\Documents"

But that is not the case, so I decided to "reformat" it and upload it as a steam guide to make it more accessible. Its actually kinda funny how some things mentioned here are so similar to my guide, given the fact that I made my guide without prior knowledge of this document, you can check it out here:
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=3051026290

(not a brag just a funny observation - for example how they also mention the messed up vertices at the modeling step, makes you feel a certain connection with the people who made these models in the past and faced the same issues :D)

While I try to handhold as much as possible in my guide from A-Z, this one is a bit more bare bones, but still could give some additional insight, if you wish to create your own mod creature, but keep in mind this guide was made in 2002, way before IC was added to the Steam.

Some things I noticed:
- Some bones visible in this guide do not appear in final wolf model.
- I would advise against using "Mirror tool", its better to use "Mirror modifier".
- The process described in "Vertice and Limb info" is indeed useful to quickly reload vertex and limb assignments, however I was unable to make it work for models made by myself (gmax just crashes), it does however work on the 3 available gmax stock models - wolf, lobster, archerfish. So if you start by tweaking these models you might be able to make use of this process.

In this guide an example is shown on how to create a dachshund from wolfs model:


In the "Way back machine" link there was also a "gif" available showcasing the process, I uploaded it here as separate images:





So that's all I have say, the following text is pretty much 1:1 from the Relic guide itself.

The idea of this tutorial is to give you a quick-start to making your own Impossible Creatures! You should have the Boner.doc and Pipeline.doc – both available in the RDN download - handy while you are making your first critter. Once you have made your first model, you can apply what’s in here towards making more and more advanced versions beyond what Relic has provided.

This tutorial is going to focus on modifying an existing IC combinable creature. It will require no
additional geometry to be created, and will reuse the bone and limbing assignments from the Wolf. More advanced techniques can later be used to create horns, antennae, and various other modifications, as well as other body types such as swimmer, flyer or even bipedal creatures. However, this is by far the easiest way to get started making new creatures for IC.

Note: Save your work as you go into different files in case you make a mistake!

The Impossible Creatures stock animals are modeled in such a way that the combiner knows how to cut them apart, and sew them back together to make a wild new combo. In this section I’ll show you which patches belong to which limb, and tips on making your combinations look great! Once you understand this, modeling your creatures and making them animate and combine properly is a whole lot easier. Because about 60% of all the creatures share the same starting base model and vertice and limb assignments, they also share similarities in the way they are constructed.


Original Wolf model

Each of the highlighted sections represents a specific limb, and even after we have manipulated the vertices to make a new model, we have to keep those same sections distinct and combinable.


New Dachshund Model

Things to keep in mind in this respect are:

1. The Head limb begins 1 row of patches forward of the front legs
   
2. The Tail limb begins 1 row of patches behind the rear legs
   
3. The Connection Rings where the legs join the body should be kept somewhat square. Try not to distort them too much, and keep them somewhat vertical.
   
4. The connection rings for the Neck and Tail should also be kept as vertical as possible. Some deviation is okay, but a horizontal connection is no good. (Note: later tutorials will show how to make a bipedal creature – but even they have to have a somewhat vertical neck connection ring)

In here I’ll show you how to make a cute little Dachshund out of the Wolf model.

The basic idea behind making a creature is as follows:

1. Extract vertice assignments and limbing info from a base model
   
2. Remove Boner from base and hide skeleton
   
3. Move points on existing geometry to form a new animal shape
   
4. Adjust skeleton to fit new model
   
5. Reload vertice and limb assignment files.
   
6. Export
   
7. Test in ComboTest.exe by combining with other animals
   
8. Go back and fix and problems
   
9. Repeat steps 2-9

In this tutorial we want to reuse as much as possible from the existing Wolf model. We are going to extract the information that tells the vertices which bone they are modified by, as well as what geometry belongs to which limb. These designations are at the heart of the combining and animation systems.

To extract the vertice and limb information:

• Open Gmax – IC Game Pack found under the Start tab at Start\Programs\Relic\Impossible Creatures RDN Tools\IC Game Pack
  
• Load the Wolf reference file provided in the RDN download. The default location this would be installed is C:\Program Files\Relic\Impossible Creatures RDN Tools v1.1\DataSrc\Art\EBPs\Stock\Wolf\Reference\Ref.max
  
• If the textures do not appear (i.e. the wolf is all gray) you have to remap the map-paths. Do this by clicking the utilities tab in the top right hand corner (the little hammer) and pressing Map Path Editor. Hit the Edit Bitmaps button and the select all of the listed maps. Then press the […] button at the bottom to browse for the texture location. They are found in the ..\Wolf\model directory. Save the file. Repeat this for the other models to ensure that your textures show up when you load the file.
  
• Save out the bone and limbing information from the Wolf. Do this by clicking on the skin geometry of the Wolf model and then under the Modify tab selecting Boner. Click on topology and then select Choose Patches. Select all of the geometry of the Wolf by dragging a selection square around it.
  
• Press Choose Anchor Patch and select the patch 1 forward of the left front leg. This can be tricky to get some times, so spin the model around a bit and click near the center of the desired patch to get it.
  
• Press Choose Anchor Edge and select the top edge of this patch.

• Once this is done you are ready to save out the vertice assignments for the Wolf model. Click Save assignments, and save the *.vaf file to your hard-drive. This file designates which vertices are affected by which bones, and will be used by us to transfer that info from one creature to another. You can assign the vertices one-at-a-time by hand (with certain specific limits), but for the purpose of this tutorial we are going to use the existing information. Repeat this process on the other RDN models to extract their assignment information
  
• Next press the Save button to save out the limb and connection information *.bmi file. This designates which parts of the creature make up the legs and how to stitch them together when we throw it through the combiner. Later tutorials will show how to make your own limbing files
  
• Now we have a starting mesh, a starting skeleton, the vertice assignment file, and the limbing and connection information. We are set to make a new creature….

• Go into the modify stack for the Wolf, right click on Boner and select Collapse All. This will effectively clean off the mesh and allow us to work fresh.
  
• The models are made from patch-meshes which are made up of vertices and handles to describe how the patch curves when subdivided. The very first thing you should do is set the Surface View Steps to 0, in order to make the model easier to manipulate. You can find the value under the Editable Patch modify tab
  
• As well, make sure that Backface culling is unchecked when you are modifying a mesh, otherwise you may easily miss a vertice or two. This can be toggled by selecting the mesh, and then looking under Edit\Object Properties for the option. Turn it off.

• Cut your mesh in half to make modeling easier. Do this by selecting the mesh, and entering Patch mode. Select the left half of the model in the Top viewport and delete those patches. Be very careful not to delete anything across the middle line, and just as careful not to leave anything behind. Trouble areas are in the tail-tip and mouth area.

Patch Mode

• Enter into Vertice mode and pull points around until you reach the desired starting shape of your critter. This is easily the most time consuming part of making a new creature, but you’ll really start to see it take shape
  
• When you are comfortable with the size and shape of the model you can set the tessellation value back to 2 and begin adjusting the handles between points. Be warned though – your critter is going to look pretty messed up right after you increase the View steps. Manipulate the handles a bit at a time until it takes shape. After a while you will get used to working with patches.
  
  
  • One tip with the handles is that shorter is usually better than longer, especially in areas like the legs which will bend a lot. If you are finding crinkled areas that you just cant work out, try shortening all of the surrounding handles and then working them into the desired shape.
  
  
• Once you are satisfied with your creation you can mirror the mesh across the axis and weld the points back together. Do this by pressing the Mirror button and selecting X-axis and Copy.

• Attach the two sides together by first selecting the Right-hand-side, then scrolling down under Editable Patch until you find the Attach button. Press Attach and then click on the left side. The two pieces of geometry are now considered one. Press the Attach button again to exit this mode
  
• We now have to weld the midline points together. Make sure to have Backface cull unchecked. Then in the Top Viewport, very carefully select all of the vertices that lie along the middle axis. It should say 80 Vertices Selected for this model.

• Now the tricky part… welding. With all of the midline points selected, scroll down to the Weld dialog and set the tolerance to something really small like 0.00005m. This value tells Gmax to weld vertices that are within this distance. If the number is too high, then parts of the model will weld that we don’t want to. This usually happened in the mouth area, so get ready with your undo button as you start welding. I always zoom in on the mouth area and watch to see if any of the lines move when I hit weld. If they do, I hit CTRL-Z, lower the tolerance setting and try again.
  
• If you have successfully welded then the bottom of the Gmax window should say 40 vertices welded.
  
• At this point you should check your model’s Object Properties to see what the vertice and patch counts are like. If no geometry has been added (like a horn), and you have welded correctly, then it should have exactly the same values as the original wolf.

Since we are intending to use the original vertice and limb assignment info from the Wolf, we should use its skeleton as well and bend it into shape. Almost all of the IC animals use an identically named set of bones, which have been adjusted to fit the shape and scale of the new creature.


These models have the same starting Skeleton

Just as with the mesh, working with only one half of the Skeleton is easiest.

• Delete all of the bones on one side of the creature including the legs, wing stub-bones, and ears. Do not delete any of the spine, neck or tail bones that run down the middle. When we have one side of the bones sized and arranged correctly we can use a plugin called BoneCopy to mirror them over.
  
• Start by moving the pelvis (which is the root of the entire skeleton) into place. It should sit somewhere between the two rear legs.
  
• Then check to see that the Pivot point is where you would like it to be. You do this by selecting the bone and then entering the IK tab and selecting Pivot\Affect Pivot only. Then you can manipulate the pivot point and line it up how you would prefer. For simplicity sake I like to put the point near the end of most bones, but you don’t have to work this way.

Adjusting the Pivot Point

To change the size of a bone:

1. Select the Bone and press the Modify Tab.
   
2. Adjust the Length, Width and Height under the Parameters section.
   
3. If you want to move the box without moving the pivot, repeat the steps for the above Pivot Point manipulation but press Affect Object Only instead. This will let you move the box freely without affecting the pivot or any of the hierarchy beneath it.

• Once you are satisfied with the layout of one side of your skeleton, copy the legs, ears and wing stub-bones over using the BoneCopy plugin. This can be added under the Configure Button Set menu, by adding a Button and then dragging BoneCopy onto it. While you are here, you might as well add one for BoneMirror – an animation plugin you will be using later.

• Select the top bone in one of the legs to be copied, make sure you check Include Subtree and press Create Copy. You should now have an identical mirrored leg on the other side. Repeat this until all of the legs, ears and stub-bone are mirrored.

Once you are satisfied with the layout of your skeleton it is time to reapply Boner and load on the vertice and limb info we copied from the Wolf.

• Select the mesh and under the Modify tab, scroll to the bottom of the list to add a Boner modifier.
  
• Hit the Assign button and assign all of the bones to this mesh. If you miss any of the bones, your model will not animate properly.
  
• Start by pressing Topology and choosing patches, then follow the same procedures that you used to save out the *.bmi and *.vaf files in the first place, except this time load the data onto your new model.
  
• If all went well you should now be able to rotate bones and watch your critter move!

The next thing you need to do is a little housecleaning. You must now change the name of your mesh from “Wolf” to “Daschund” or “Ichthiosaur” or whatever your beastie is. Since we copied all of the limb
assignments from the Wolf, and loaded them onto our new critter, its limbs and connections are all prefixed with Wolf_ and need to be changed as well.

• Click on the creature’s mesh and then under the Boner modifier select Limb
  
• Press Edit and then scroll through the list of limbs changing the named prefix to your new creature’s name
  
• Do the same under Connection

We are about to export the creature and do some testing, during which time we’ll be yanking Boner, tweaking the model\skeleton and then reassigning Boner. We have made naming changes to the limb and vertice assignments, so we should resave out new files so we don’t have to rename each time we load them on.

• Follow the steps for saving out the limb and vertice assignment info, and save them in the folders of your new creature. It doesn’t really matter where, as long as you don’t confuse them with the ones from the Wolf.

• Read through the Pipeline.doc that came with the RDN download for a full explanation of where your files should be saved to and how you can export them.
  
• Once you have exported and saved out your Dachshund.sgm file, you can open up the Object Editor, Create a new EBP and load in the *.sgm file. Save this out to Dachshund.EBP when you’re done.

Note: You will not need to create a new EBP each time you edit your model. The *.sgm is overwritten when you export and it changes the look of your critter in the EBP.

• Open up the ComboTest.exe application and try combining your beastie with the wolf, lobster or archerfish. If you find any problems, go back to Gmax, remove Boner, adjust the model, reapply Boner and load the saved assignments, rexport and test the combining again.

Trust me, after your first creature this gets way easier!