Ordinary IEMs don't seem very comfortable to me. I believe it has something to do with how my ear canals appear to be about twice as tall as they are wide. I know that because I got a set of custom ear plugs recently. Because of this, small foam tips aren't secure and medium foam tips form a pressure point, and the silicone tips are much the same.
So that's why I'm looking around for other options. Are custom tips for normal IEMs at all common? I don't see them brought up very often, so I assume there are some kind of disadvantage to them? (Or maybe just lower margins) Are there any IEMs with stock tips that are proportioned like my ear canal? I didn't pay much attention at the time, but I seem to recall the older Ultimate Ears universal fits to have elongated tips. I've seen both silicone and hard acrylic IEMs, what are the advantages and disadvantages of these materials?
I still have the impressions from the ear plugs, but they were done closed mouth so I don't think they're very deep.