Here is my latest project of a laser inlay kit, made of black dyed spalted maple, cocobolo, and natural curly maple. The kit comes with 5 pieces (tube,4 pieces of wood) and assembly instructions. Since the laser has cut the openings for the rifle stock, barrel and the scope, it is required to insert the tube into the main body (curly maple) then pressing the the fitted pieces into there position. Then removing the tube form the body, and using CA thin glue (which dries almost immediately) onto the inserted parts and let dry.
Next try inserting the tube, however it may have been that some of the glue leaked through to the inner portion of the body. In that case taking a small dowel or pencil and wrapping a piece of 220 grit sand paper to smooth the inside until the tube can easily be placed in the body. Using a two part epoxy glue, coat the tube with the mix, be sure the tube is centered in the body, and let it dry over night. Sand both ends so that the tube and the body ends are flush. Turning this asssembly is critical and make sure the turning tools are sharp. Place on the lathe, I like to use 220 grit sand paper first to take the rough edges off the rifle parts if there are any slight protrusion. Then using the same procedure of finishing as in the previous posts, with 320, 400, 600,1200, 1500 grit, turners polish, and then the assembly is being done with a Mesa pen kit.