Thank you all for your answers. The proof paper is 0.04 mm thick. This fake was in a lot received from an uncle more than 30 years ago. It was not pasted on a cardboard paper.
It is a very bad forgery as you mentioned, arms, nose, .. I did not find the model in https://stampforgeries.com/forged-s...triangle-1s/
I can't find the model .
Why make a fake as a proof? SG does not mention proofs