there is paper sides use a clear urethane or similar to coat the labels i have found it eiser to do this before you cut them out i have used pledge floor finish for my labels i have tried urethane on the first few with the same results

just use what you have i have also thought about pledge furniture wax 3d printing is more about just plain experimenting than anything else even thought about hair spray as a protective coating ???

or you can just be cheap and just print the labels on card stock and glue the side 1 to side 2 with out even 3d printing the plastic

then when dry put it between 2 pieces of paper and turn on your iron and set to synthetic and iron flat this will take the wrinkles out from use of the urethane

use spray glue and spray the ruler cut and place for the french curve ruler start with the start label and cut the whole out of the paper as well, use this hole to align the paper with the ruler the rest will just basically align with the edges then take a knife and cut out the other holes

for the square for side 2 you will use 2 side 2 and 1 side 2
for the square for side 1 you will use 2 side 1 and 1 side 2

best to lay out the square ruler labels before cutting them out

if you mess up any of the paper labels you should be able to just pull them off and start over if you are having a hard time with them use a hair dryer to heat the labels this will make the glue soft and the will peal off with ease