i do this all the time. i have however not found them very helpful when done real thin. well anything helps but when the corners curl, if the discs arent stiff they seem to just lift right up. i guess it depends on the model though and how strong you need them. i keep them modeled and in a folder as davo said then just drop them on the build table. drag them where you want them and your good to go. usually mine vary from 5-7 layers. not sure with pla as i never print it but in abs they just pop right off no problem and you cant even see where they were.