Two possibilities occur to me to circumvent the problems:
(1) Self-adhesive ferrite strip where the magnet is to be used, allowing 304 stainless for the door construction
(2) a layer of 0.5mm 304 stainless covering a strip of 430 (or similar) grade magnetic steel, to keep the surface "truly...
No, not a motor driving a peristaltic pump, but a motor producing rotary motion from a compressed air supply.
Only place I've seen this done was on an episode of BBC TV's "The Great Egg Race" from the 70's, where a team were tasked with building a motor and given assorted clutter with which to...