They aren't as hard as they seem
I've been trying for a while now to figure this out. I've scoured the internet, and this forum, and I haven't found the information that I feel I needed. If you feel the same as I do, I hope this post is helpful to you.
There are a few things you'll need for this, but not many.
-WinRar: http://www.rarlab.com/download.htm Find what matches your OS, and get this
-StarCheat: https://github.com/wizzomafizzo/starcheat/releases I use "starcheat-39219c2-win64.zip" but, if it works, it works
-DrawablesGenerator: https://github.com/Silverfeelin/Starbound-DrawablesGenerator/releases I use v1.1.1 for win32, as OS does not seem to matter
-Image Editing Software: If you have a PC, you probably already have Microsoft Paint. Yet there is also Paint.NET which is easier for some as it allows transparency. (when getting it, be weary of fake download buttons. Use this link to make it easier http://www.dotpdn.com/downloads/pdn.html)
-[Optional] Notepad ++: I find it's easy sometimes to copy and paste code to and from a .txt file, but it is far from necessary
Doing The Do:
Start off by understanding where things are in StarCheat. Open the .zip, run the .exe and select a character profile. From here you can right-click a slot, hit edit (not edit json), and search for a gun to use as a base. My example will use the Durasteel Assault Rifle. But, I believe this works with most guns. Confirm that you want the gun, and it will be there in your inventory.
Now, you ought to make a gun in Microsoft Paint. Look up references on Google, be creative, be realistic, be whatever you want. Just follow the server's rules. Here's one I made. It's just an assault rifle. Use it if you want, edit it, whatever.
Next, you need to translate it to code. So, open DrawablesGenerator, run the .exe, and select your image. MSPaint does not support transparency, but this program is forgiving. Where it asks for what color to ignore, use ffffff for white. Or, any other hex code. I'd stick to white or black though. If you want pure white in your picture, and still need transparency, paint should show you at least what the RGB is (in edit color) if it shows hex, perfect. You're smart, you can use Google if you need to. Or, comment and ask me.
Once that's in, you'll notice, it's off. Mess with offsets to make it sit where it looks good. And, edit your picture if you need to. Looking good? Hit "plain text" and you'll see a bunch of code pop up. Don't be scared. We're almost there.
Use this animation.txt for the next part.
In StarCheat, you need to edit that item you added. Go to the animation part (It's easiest to tell it to edit json when you open the animation section). Replace everything in there with all that is in that .txt file. In the output from the DrawablesGenerator, you will see something like this:
"image": "/objects/outpost/customsign/signplaceholder.png? XXXXXX
And, possibly more than one. (D_1, D_2, D_3, ...)
Copy them to the corresponding spot in your animation area, replacing what is above. It's easiest to copy from the "D_1"... to the -0.X of the very last D_X section. Make sure you have all of them.
And, accept the changes.
If you have issues with a pesky secondary function, you can just remove all text from the alt ability area. Or, find another that you prefer through the use of Google, or unpacking assets.
If you want to change sound files, look for the animationCustom area, and replace what is there with another ingame file. I do not know what sounds can be used, but you can unpack assets, and find that out. There are easy tutorials out there on how to do so.
That's it. Load it up, and you have a drawable gun.
This tutorial is only the bare minimum in terms of complexity of drawables. But, it was so hard for me to find out how to do this at all, and I wish there was a tutorial out there like this when I was trying.
Please tell me what to add/edit. Please ask for help if you need it.