Get a piece of 8x10 paper ( printing paper and roll it up and tape it.
The trace out a Mauser c96 body ( shown)
Then put another piece of paper behind it and cut.
Cut out two or more strips of paper and put Aron sides and join the two together.(leave gap at bottom of aware and front)
Then put barrel in and tape then cut the barrel if too long
Cut two little 1/4 inch part of the excess barrel. And tape on sides
Then maze a rectangular prism to fit snug in the bottom