Since the late 80's I've routinely carried all 4 tools below the ruler.

Spring steel clip to hold pant legs out of the chain.
Hemostat to hold tire valve out while inflating an empty tube.
Blackburn brake holding block which is like the carved block of wood idea to hold caliper brake levers locked.
(Note the 3 steps to hold 3 different size levers in fully locked position, the two edges have two sized grooves to snap lock it on either a brake cable or a smaller shifter cable for storage).
Halt clip: one end clips on bars the other around can of HALT.

Thanks to this thread I am now throwing them all to the junkbox.
I find the rubber band on the left (size # 64) way better for all 4 purposes!
Rubber band on the right is size #62.
Both 62 and 64 are 1/4 inch wide.
Size 32 would be 1/8 inch wide.