As the title states, this is indeed a study of cardboard as a material to make a sheath from. The hope was that if I could provide a cardboard sheath as a cheaper option to making a wood one both in time and expense. I tried to keep track of the things I learned in the process of making this.
Now cardboard has a few pros and a few cons when it comes to making a sheath. It's light, fairly sturdy in one direction, cheap, paintable, has a straight surface, and easy to cut/work. The cons are that it bends easily, isn't waterproof, and has a less than ideal surface finish. My plan was to try to minimize those cons through various techniques.
I started off by making a poster board template that could be transfered to the cardboard. I had to make sure that the top edge would fit to the hilt of the dagger, and that there was extra space for the edges to meet without pinching the blade.
Once that was done, I traced the template to the cardboard and cut it out. The important part here was to make absolutely sure I didn't bend the cardboard. That would crease it, and ruin the strength and surface of the cardboard. Once both pieces were cut out, I scored down the middle and bent the cardboard into the shape I wanted.
Next I painted the inside with primer. This made the inside a little more waterproof, and thicker which increases the strength a tiny bit. Also, the paint could be sanded to a smooth finish.
Then glued the outside edges. This went quite poorly. I used hot glue, which is just plain messy. I know it's messy, and my plan was to use wood filler to go over the glue, and sand smooth. Not my best plan. It might have worked, but my wood filler was old and crumbly, and my attempts to smooth the glue with the end of the glue gun went horridly. I could have done that much better here.
Once it was glued and the filler sanded, I painted it with primer on the outside. Now my mistakes really showed through. I had ruined the surface with glue dollops, and the edges looked like garbage. I really should have stopped here and either tried again or moved on. But no, I R STUBBRN>.
I decided to try my plan to strengthen it, and cover the sheath with canvas. I laid two coats of polyurethane on the sheath, and it did a decent job of adding strength actually. Next time I would try 3 coats, with maybe another agent laminated on, like wax paper.
Once dry, I cut the canvas out and sewed it up. Encouraged by how good it looked, I decided to continue and make the end caps from poster board. I added canvas to the end and then glued on the poster board. This came out....ok. Pretty good surface and painted up well. The big problem is the seams in the poster board which I had to fill with my old wood filler again. Left the sides pretty rough, but not miserable. After filling the gaps of poster board and painting, it looked pretty good.
In summary, while the end result didn't look too bad, I wound up putting much more work into than planned. And since I couldn't work any pretty details into the sheath, it's pretty bland for the time spent. So in the future will I be making cardboard sheaths? ....No. But I think for a very basic project or on a budget, this method could be tweaked to make a good looking sheath.