You started, you might as well lay it all out in public. I haven't done anything with paper mache since highschool and that sorta collapsed under it own weight. Any tips from from someone who's done this and had it work well would be great.
I'm thinking that if I don't have a canvas sheath to start with for a core, corrugated cardboard and duct tape or pallet wrap?
The stuff you used in highschool was probably just paper pulp mixed with water, and that doesn't have much strength. What you're going to use here are ripped up pieces (about 3-4" long) of brown paper shopping bags, very tough stuff. You're going to soak these through with thinned carpenters glue (Tite Bond or Elmers). You'll need about a pint.
The glue comes out of the bottle too thick to use, so pour a fair amount into a glass bowl and thin it with water, to about the consistency of cream. If you get it too thin, just add more glue. Mix it up good.
If you have a canvas sheath to start with, make a folded cardboard insert to go inside to stiffen it up. This can be wrapped with duct tape of your choice. The belt loop on mine was flimsy cotton webbing and I beefed that up by cutting a strip of horse hide and using DAP Weldwood Contact Cement to glue the leather over the webbing; making sure that one end went well inside the sheath...and the other end went far enough down the back of the sheath to be covered over with the paper layer.
Now give the outside of the sheath a coating of the glue mix with a brush, sort of a primer. You don't have to wait for it to dry, this just gives the paper strips something to bond to.
I said this was a kitchen counter project because your hands are going to get messy with glue and your going to want to wash them in the sink. The glue is water-soluble while it's wet, but pretty hard and waterproof when it's dry. Lay down a couple of sheets of waxed paper to protect the counter.
Now that the canvas is primed, start soaking a few strips of paper in the glue mix and start laying them onto the sheath. Start at the bottom tip, wrapping around the curved edge, and start laying them up to the top. Make sure each piece overlaps the previous one. You're going to have to use your fingers to smooth them down nice and tight. Wipe off any excess glue mix.
Once the curved edge is done, start filling in the middle of the sheath, front and back. Then do the back edge. When it's covered to your satisfaction, set it aside to dry. If inside, you might have to wait overnight, setting it outside in the sun will speed it up.
Once it's dry, you can sand the rough spots lightly. If you want to add more paper, have at it. The beauty of this stuff is that you can keep building on it until it's as strong and thick as you want. When dry, it's fairly light weight.
When it's finished to your satisfaction, you can give it a sealing coat of clear polyurethane varnish and call it done. If you want to stain it, do that before you seal it, I would recommend something like leather shoe dye. Or you can get artistic and paint in a camouflage pattern, or your personal logo, or a death mask, etc

You can do a quick and easy leaf pattern by gathering a few leaves from outside, lay them over the sheath, and spray it with black, brown or green paint. Lift the leaves off and you have a nice negative leaf pattern (I got that from watching Martha Stewart

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I use brown paper bags because they have a natural color; I rip the strips by hand because that gives the paper an irregular feathered edge, natural and organic looking. You can cut them with scissors, if you choose, but I think the straight edges would look funky.
IF YOU DON'T HAVE A CANVAS SHEATH: Get a good heavy duty cardboard that you like and fold it in half. (If the cardboard is coated on one side, make that the inside of the sheath...you want the natural paper side on the outside)
I haven't tried this yet, but if you want the handle of the knife or machete to go inside the sheath, I think you could wet the cardboard at this point and mold it around the handle, just like you would with leather.
Lay your blade over the cardboard and cut out the shape. I would make it about 1/2" extra large. Before you tape it up, add a leather belt loop. Cut it out of a scrap of leather or cut it from an old leather belt (find those at the Salvation Army thrift store).
Glue the belt loop to the front and back side, on the back side of the sheath, with Weldwood contact cement. Then re-inforce it with stitching or a couple of rivets, or grommets.
Then use a thin strip of duct tape to seal the front edge of the sheath. I say a thin strip because I'm not sure how well the carpenters glue will adhere to duct tape. Then proceed to prime the sheath and lay on paper strips as mentioned above.
You can get as creative with this as you want and mistakes can be easily fixed. Good luck and show us some pictures
