Could you add spaces, and 1234567890?/'";:>.<,[]{}\|+_()*&^%$#@!
Several of those already exist.
0 could be two rotated c's with each one rotated in a different direction and two I's
1 could be a bent 7
2 could be an upside down U (or a turned C) and a doubly turned 7
3 should just be two horizontally flipped C's
4 could be a vertically flipped L and 2 I's and 1 rotated I
5 could be a rotated and flipped 2
6 and 9 should just be O's with J's
7 could be a bent doubly turned L
8 should just be two O's
* could be an upside-down V with 1 I and two rotated I's. Triangular brackets should just be sideways V's.