This is a model I made of Jazz's G1 gun! It's pretty easy to print, and will fit on a standard Ender 3-sized bed with no issues.
Because I have a young son, I added some spots where you can connect the “fuel cell” and the clip with magnets. He never takes those out on the show, but like I say, I have a young son, and “reloading” action is fun. If you want magnets, you'll need 6 6.4mmx2.5mm magnets. If you don't, you can just glue the pieces together!
The author hasn't provided the model origin yet.