Press tab (by default) to switch to command mode, then press 3 (by default) while hovering over a bulding to view its blueprint. Then, copy the blueprint into your personal fleet and edit it - you should see the new blueprint in newly-loaded sectors. Again though, don't be surprised if this causes a lot of crashes.

how do you even make a building?

I find the weapons too weak in the Start. The beam weapons can't seem to cut anything. The swarm missile Helps but it's range is too short in my opinion. Like when I can't even go toe to toe with some of the bigger RED ships... yea feels underpowered couldn't keep playing to get the Station Launcher to see if it's worth it or not...

The mod has 200 errors and the parts appear in Faction 8's (Terran) construction screen. It is also incompatible with Terran Reinforcements and Expanded Armoury somehow, probably due to this mod overlapping in mod IDs.

Heavy palette confliction with Owlfeather's Expanded Armory.

H E X A G O N S are the B E S T A G O N S

Nice mod man.

Where all of the ship designs are shown.

What's the fleet screen?

crashes*

I've heard from several sources (such as the reassembler mod's page) that crashed can occur if a building is in the fleet screen.