I use the same idea...just hand written on white business cards...I use business card sleeves that you can buy in pages as Staples and cut them out...then to attach them to the tubs I use 1 inch round velcro from K mart with sticky backs...hard ones go on tubs and soft ones go on plastic sleeves.
That way if I move a snake I can move the card...really only use them around breeding season to keep track of shed....OB's and date on eggs laid...
I dont label my tubs with what is in them...I use large black bundle paper clips and hang key tags off of them with numbers and then keep a master log for each snake morph and their number in a book....that way if someone breaks in they are going to have to go through every tub to find out what is in them.
When I hatch snakes I use the number tags for stock numbers...for example males number goes first....8 being one of my pied males, 24 being het pied female so hatchling stock number is 824 then sex 824F then order I sexed it in
824F1 would be Pied male 8 to Het pied female 24....female baby number 1.
Then hang a tag with smaller bundle paper clip off of shoe box with that number 824F1 and it follows the snake around the room or until sold.
Just my system...thought I would share.
Travis
Lair of Dragons