Wallet comb that has the same size of a standard credit card (and double the thickness). This can easily fit into your wallet and is strong enough not to easily break, even when printing with PLA.
The bond between perimeters and infill is not as strong as the bond among perimeters themselves. So, tune your slicer to use as many perimeters as needed, to print the full piece without infill. Pay attention to the picture, you can see the perimeter lines go to the center of the piece.