This is a alterd model of the Lego Katana, meant to be assembled with a carboard tube from your recylcing can to resemble a Tanto blade. I used the tube from my empty roll of alluminium foil, but any size tube will work obviously. To properly scale the model to fit your tube, match the external diameter of the flange (widest part) on the blade model, with the internal diameter of your tube. Scale the other parts according to how you scaled the blade model, a simple percentage calculator website could be helpful.