I’m wondering if water-soluble filament could be used to cast complex epoxy shapes. Any thoughts as to whether the liquid epoxy would dissolve the filament? Is anyone interested in joining me in experimenting with this?
EDIT: Hm… just found an Instructable that covers using ABS molds and dissolving them in acetone… sounds much harsher than water-soluble support filament. I haven’t printed with water solubles yet, not sure what kind of finish quality they have.
Looks like water-soluble PVA or D-limonene-soluble HIPS are candidates. PVA looks to be the more expensive option at about $60-$80 a kilo. Here is a listing for HIPS with 4+ star reviews for $20 a kilo… but the D-limonene is about $80 a gallon. Sooo… maybe the choice is kinda even price-wise. I’ve never used D-limonene so I don’t know how noxious it is, if at all.
The deciding factor would probably be which one has the best print quality since any imperfections will be transferred to the cast epoxy.
It sounds relatively safe, though topically it may be irritating. Safety evaluation and risk assessment of d-Limonene - PubMed
All the water-soluble PVA prints that I’ve seen look hideous in quality… even in the ad for it on Matterhackers.
I’m not terribly sensitive to things like that… in fact, I’LL probably irritate the D-limonene. 
The downside may be the HIPS turning into a gooey sludge.
I say we just give them BOTH a shot. I’ll print a Benchy with each… then dissolve them like the Wicked Witch!
D-limonene is a citrus oil, safe enough to be taken internally. If you haven’t seen irritation using lemon oil as a furniture polish, you have no reason to avoid it.
And, it might repel mosquitos as well as DEET, especially when combined with Geranium oil.
When I’ve printed with PVA as a support it certainly didn’t look great, but I’m not sure how much effort has gone into adjusting those profiles for quality. We do have a spool at the makerspace.
I’ll try to do a slow boat Benchy. Prolly need to bring my filament dryer and cook it for a bit.
