Cool definitely worth a try. I have a bunch of canal phones I can't use for more than ~15-20 minutes because the silicone sleeve tips tickle the little hairs in my ear canals. Its maddening! Gives me chills and makes the hair on the back of my neck stand up on end.... UGH... I have some GREAT sounding canal phones I can't enjoy for more than 3-4 songs without removing them and cramming my pinky in there to alleviate the tickle sensation.
A mod like this might alleviate this if it can properly seal around the outer canal and not deeper inside. The cotton/foam on a string is used to make the mold positive, for when the audiologist takes deep insertion impressions with the syringe. Its not needed with a kit like this since they are not injecting the material deep into the canal with a syringe. That and the fact that this kit is not making a mold positive, the impression is the actual end product.
One concern I would have is many dynamic driver canal phones have vent holes to alleviate pressure / vacuum on the driver diaphragm when inserting and removing them. Some phones "crunch and crackle" when you insert them, thats the diaphragm compressing from the pressure. A mod like this doesn't look like it has any way to allow for proper driver pressure venting.
Curious, does anyone else have the same problem with little hairs inside getting tickled constantly with canal-phones?