Where can I find a replacement for the foam between the heat sink and

I recently replaced the fan for my nintendo switch, and was not able to recover the foam tape that went between the heat sink and the fan due to some exceptionally stubborn adhesive.

Does anyone know of a suitable replacement? The only thing I had on hand was a 0.5 mm thick thermal pad, so I cut that into appropriate sizes and applied it to the heat sink. Is that an absolutely terrible idea? I haven't really tried to put that switch through the ringer to test the thermals, but it's been working fine under light use.