I get asked this a lot: how to build a kitgun. This guide will go over how I personally build my own kitguns, zaws, and pretty much anything else that is modular. Please note that this is to personal taste, and basically to each their own. Now let's get to it!
Going to start this off with the fact that I usually build my kitguns and zaws around rivens I unveiled. My approach via this method is that a) I already know what I have as a strength and as a weakness in the mod and b) I can compensate for the lack of a stat. This doesn't mean that you shouldn't or cannot build one without a riven mod. In fact, I'll go over that in the next section below.
Kitgun With Mod
Father has a decent amount of parts, just like Rude Zuud over on Fortuna and Hok over on Cetus. Don't let this overwhelm you. What you are going to want to do is click the option: Build Kitgun. This will open up 3 slots where you can select a choice to build. First slot is what the riven mod is for, which in my case it was a Sporelacer. For this example, I'm going to pick the Sporelacer chamber (description: fires spore-sacs that rupture into three smaller toxic projectiles on impact.). Next up is the grip. For this kitgun, an Ulnaris will work great, mostly due to the increased fire rate/decreased damage delivery. If I didn't have the mod with the damage, I would probably go with the Haymaker grip instead. Finally, the loader I will pick is the Arcroid. This is mostly due to the mod I have again, adding a little extra critical and status chance to my overall build (remember high damage mod). I feel like the loader is probably the area that you can do whatever you want and probably not screw it up bad.
Once you've selected all 3 parts, you should see the stats it will have right off the bat. The best part of this stage is that you can pick and choose various parts and see what the stats end up being. Nothing gets committed here. After picking out your parts, go ahead and purchase them from the Browse Wares option. Build the parts, slap it together, then go out and level it up.
NOTE: Some times I find a kitgun or a zaw build that I'm iffy on. Best advice I can give on this is to a) guild it and b) try adding arcanes. These can make a big difference. If you're still not satisfied with how it feels, take note of what you did and rebuild. I've screwed up a few times while building these things, so don't feel like you can get it right the first time.
Zaw Without Mod
I have built a few of my kitguns and zaws without a riven mod. By doing this, I have them done, got the MR for them, and have them available for when I DO get a riven mod (if I decide to keep it). For this example, I'll be using my first Zaw I built and have kept for whatever reasons. Head over to Hok on Cetus and let's get to it.
So, this was my very first anything-modular weapon. Wasn't quite sure what I wanted out of it, but it still slaps. As we did in the previous section, click on the Forge a Zaw. For this example, the Strike will be a Mewan (more damage but slower in speed). I want to aim for a polearm weapon because personal choices, but you can pick sword in this case (or whatever strike you want to choose). The Grip I'll pick is the Kroostra, for an additional damage and slower speed. This keeps the polearm build, but if I would rebuild it, I would pick the Shtung. The reason being is that it provides greater impact and strikes, without the speed hit. Lastly, the Link section. I'll be honest, this part gets REALLY confusing for first time builders. The names are very similar to at least 1 other link, let alone the descriptions. Let me make this very clear: click one each one that piques your interest, then look at the stats. They do change and they do make a difference. For this example, I will choose the Vargeet II Jai to help balance the damage and speed, with the additional help of critical stats. With the help of mods, I can build this Zaw up to being a decent melee weapon.
|Vargeet II Jai|
|Vargeet Jai II|
If you do want to go the Zaw route for default melee, I highly recommend getting a plague part. These little suckers are infested right off the bat and can give an additional pain factor to enemies.
I hope this guide helps demystify the whole building modular weapons in this game. When I say that I've struggled with building some weapons, I mean it. I've screwed up some Zaws so bad, I couldn't even get them to level 30 before destroying them.
Happy building, Tenno!