A few extra odd shapes would raise the ° difficulty, however, to have more than 1 solution would require greater investment of time... and for freebies, enough is enough. Though for some puzzles I have put in wrong pieces or duplicated one for a required missing piece for gift to people I'm not too fond of.
For my alphabet puzzle I made 2 sets with two "Z" and no "A"... there was "A"s (7 x "Z" and 5 x "A") in the set but not in a solvable configuration... it took more effort to make up that set than to solve the good ones.
If your first cut is too short... Take the second cut from the longer end... LBD
