Mary uses an ancient paring knife (that, back in the day, my father had sharpened beyond all reason) to harvest garden veggies, which called for a scabbard to protect the blade, the bike pack, and the fingers.
I snagged a random block of acrylic from the heap, straightened the long sides, milled a channel just wide and thick enough for the blade down the middle, then added small recesses at the right end for the knife’s haft:
The cover is an acrylic sheet, solvent-glued and clamped in place:
The cover exposes about 1/4 inch of channel so she can lay the point in place, rather than precisely aligning the point with the slot. I suppose I should have used gray acrylic to provide some contrast; maybe we’ll add a snippet of tape.
Then mill four sides flat, break the edges & corners with a file, and it’s all good (in a blocky kind of way):
The blade has become sufficiently bent over the years that simple friction holds it in the slot. It’s open on both ends so she can flush out the inevitable dirt.
I was going to engrave her name on the back, but came to my senses just in time…
The Smell of Molten Projects in the Morning 
…and the Wind cries… Mary
Should have done the engraving LOL
Well, given the choice between devoting another day to getting it right or putting it in the garden now, the decision was clear!