I have never done that myself, but from having worked in a print shop, you definately want a heavier paper - a card stock might be hard to work with because it is so heavy (that's what Playmobil originally uses and then has a machine place the seams of where to bend it in.
I would suggest going to a print shop and asking to see some different weights of paper and taking a sample of the orginal paper Playmobil uses as well.
Some printers (home computer printers) will not print heavy cardstock paper while most should. Check the manual or online and see what they say. A photo capable printer will be able to and most are these days.