I apply metal heated to very precise temperatures to Nina’s cunt, and they're quite happy about it.

Several months ago I heated up a trailer hitch in the oven, waited until it cooled down to about 117°F, shoved it into Nina, and they loved it. Unfortunately, even a trailer hitch cools down pretty fast once you put it inside someone. They suggested I could put a toaster oven dedicated to reheating in my bedroom, but even having it close by wouldn’t help much. Toaster ovens are not precision instruments, and that heating and cooling process was fussy and time consuming.

Eventually it occurred to me that with a sous vide cooking unit, I could dial in an exact temperature for a water bath, put some steel toys in it (where they’d reach target temperature much faster than in an oven, without risking going above that temperature), and be able to rotate them in and out in sealable plastic bags.

That’s the pointy face of a hot meat tenderizer that I’m using in the teaser video. This was, if you’ll pardon the expression, the warm-up.

• I disclaim all responsibility for any horrible consequences if you try this yourself and it goes south. We’re still experimenting, so far it’s been a lot of fun but this might be a terrible idea. Do some research, don’t use me as your only information source, please.
• I’ve seen heat pain threshold described as 105-108°F. According to CPSC, a ten-minute exposure to 120°F water will result in third-degree burns. According to antiscald.org looking at second-degree burns, 116.6°F takes 20 minutes, 118.4°F takes 15, and 120°F takes 8. I’ve been unable to find data on first-degree burn times. Remember that these are constant temperature exposures, metal will be cooling quickly as the heat moves into flesh. I arrived at 117°F being a good target for starting temp from looking at OSHA data, but can’t find the source on that. Stainless steel in an orifice at 117°F makes a strong impression.
• Toys cool surprisingly fast once you put them in someone, compared to how they cool in air. I’ve heard that people are mostly made of water, so this makes sense. You’ll need to do a lot of re-heating of toys if you want intensity, rotating amongst a few is helpful. However: the inside of a rare steak is about 120-125°F. Don’t cook your partner.
• The physics of heat transfer is complicated, and I don’t have all the background in it that I’d like. Heat capacity and thermal conductivity of different materials are relevant. Stainless steel seems to work pretty well. Aluminum loses heat too quickly, glass and stone retain well but transmit too slowly. Mass makes a big difference- a larger toy will remain hot longer than a smaller one. I recently bought an Njoy Eleven for this purpose, and reviews are glowing so far.