my first homemade friction saver was made out of a cheap stitched dyneema 1/2" sling. I girth hitched a small ring to one end... slipped some webbing over the middle and girth hitched a carabiner to the other side(also experimented with the roller carabiner paired w/locking biner on this side). Slings are cheap that you could have two sizes and swap the hardwre when needed.
My current saver is goldstreak sliced for a biner on one end and a small ring on a sliding HRC friction hitch for the other.
For a non-spliced saver I might suggest some 8mm cord tied in a loop w/fishermans and fashioned like my stitched sling above leaving the knot on the small ring side.
These work well for me but honestly, for day to day climbing I use the Sherrill leather sheath more than half the time for ease of use, no breaking parts, and ample performance for less than $20.