This simple jig will hold your knife at the proper sharpening angle when using any flat sharpening stone on a flat countertop. The front end clamps onto the edge of the knife and the back end has a foot that can be adjusted to set the desired sharpening angle. I've also included a simple angle gauge for adjusting the foot to the right height. It is suitable for most any knife with a blade height (distance from edge to spine) of greater than ¾"/ 19mm. 

To use clamp the spine of your knife onto the front clamp and gently tighten the two screws. Tighten just enough to securely hold the blade, as overtightening may break the screws. Then loosen the locking nut on the foot at the back end and adjust the height of the foot using the angle gauge as a guide as shown in the 3rd photo. Then lock the foot in place using the lock nut. To sharpen, you'll lay the blade flat against your stone, and have just enough pressure on the foot in the back to keep it in contact with the countertop as you slide the knife across the stone.

For more tips on how to sharpen knives, types of stones to buy, etc., I recommend videos by Outdoors55.

Filament Type
I printed this in PLA-CF for stiffness because the blade clamp has only a fairly shallow grip on the blade. You probably could also use plain PLA or PETG-CF, but I would not recommend using plain PETG, ASA or ABS.