Here is one of my past projects. I downloaded pictures of this pistol from an auction site, together with the length of the barrel. I was able to paste the pictures into AutoCAD and create a 3d model that was as faithful to the original as possible. I based the replica on the Cad drawings and my knowledge of Japanese matchlock technology that by and large avoids screw threads - everything apart from the breech plug was held together with pins. Here are some pictures
Rob
Rob