I like. I like.
Saw this, thinking about if (in house) FDM is now actually reasonable for low # production. Can start with a higher durometer than usual (~50a) but with air pockets (ala purple mattress)
https://www.youtube.com/watch?v=1grf8dIMoTo
Surface finish will obviously be bad (though the texture isn't awful) - I suspect worse than SLA molds but better than soft molding is achievable with an acetone polish.
and internal reinforcements will be needed but I like the idea of custom colors for custom markers:
https://filament2print.com/gb/201-filaflex
"So you've done this before?"
"Oh, hell no. But I think it's gonna work."