Ever since I bought my crosman 1377 I wanted a shoulder stock for it, but the one made by crosman costs a ridiculous 50 euros. I would never pay that much for just a hollow shell with some crappy grips. So I designed and printed my own. Long live 3D printing!
So these models include a target grip and a attachable shoulder stock. You can use only the grip if you prefer so. The stock and the grip are seperate parts. The stock can be attached to the side of the grip with 2 screws, so you can attach and remove it whenever you want. I found it better to have the shoulder stoch off center of the airgun, so that your hand around the grip and the stock will not interfere. I quite like this, since it puts the sight just in the right position.
Also, the grip is quite basic. Everybody has different hands, so making one universally fitting grip is difficult. Instead I have left is bulky so that you can file and sand it to a comfortable fit. For this make sure to use at least 3 layers for the walls of the print.
The shape of the stock is designed in such a way, that it needs minimal support material.
Last but not least: Since not all printers have a big enough volume to print the stock in one piece, I have split it up in 3 pieces. Those 3 pieces can be printed and then glued together. I have added notches to give the 3 glued pieces the needed strength. Since I have a small printer I made mine this way and with the help of some epoxy glue it is rock solid.
0.2 for the grip. 0.3 for the stock
Use 3 layers for the outer wall. Also, print the stoch in vertical ortentation.
Post-Printing work on the grip:
The grip should fit nicely on your crosman 13xx. Some sanding might be necessary. Print with 3 outer layers, so that you can file and sand the grip to fit your hand. After I had done that, I sanded it with some 250 grid sandpaper. After that with some scotch-brite.
Post-Printing work on the shoulder stock:
If you printed the stock in 3 parts, then glue them together with a strong glue. The notches should make it a good fit. You might have to drill out the holes for the notches a bit to make it fit. After that you can finish it however you want. Once again I sanded everyrhing to give it a smooth and weathered effect. When you do this properly it wont look like plastic anymore, but rather like some sort of molded polymer.