Has anyone tried these things?

Custom Fit Earbud Enhancers: Get Fitted | yurbuds? earbud enhancers

Interesting. I had some trouble with earbuds staying in my ears but after my Yuin OK3 was mangled/destroyed I stopped caring.

I think tyrion mentioned getting a set for one of the marathons he ran earlier this year.

I tried a couple similar products - not from these people - a few years ago. One was custom molded and one was generic-in-assorted-sizes. In both cases they were pretty awful SQ-wise, but of course I can't speak for this one.

To judge from the fitting process, these really have to be generics (size preselected based on your photo), but IMO the price is on the high side for that. Of course if for $30 I could really get my Jawbone headset to fit properly, then I wouldn't care whether it was custom or not -- but the warranty is solely against defects and doesn't appear to cover dissatisfaction over fit. So personally I'll pass.

As a business case study, though, it's kind of interesting. Stock a selection of generic parts, and charge $30 to choose one pair on your behalf rather than, say, $20 to ship a full fit kit with a range of sizes. A nice markup for the custom-feeling service, and a reduction in cost of goods sold as well.

I think tyrion mentioned getting a set for one of the marathons he ran earlier this year.

I recall that as well. I thought he said they made his sound better?

They are great for what they are. There buds do sound better with them as it gets the sound closer to your ear drum. Much deeper bass, maybe too much but for running, they are perfect. I ran about half the marathon wearing them and they never came out of my ear once. That would not have been possible with just the buds.

It also appears that they can be used with IEMs.

I hereby proclaim them JH13 killers, having heard neither.