Hi! I have made Spidey's faceshell from movie The Amazing Spider-Man 2: High voltage.
Holes for magnets: Recatangular magnet: 10x5mm (2mm of depth). Circular magnet: 5mm (3mm of depth).
Also I make Web shooters. But you need to check siae of them because I am not sure about it.
I'm separated model on different part, for convenient assembly. Helmet was made for adult male head. Also if you need cut helmet for your printer, file includes uncut model.