I thought I'd share my own modding details for those who might be interested.
I love the Shure triple flange tips - other triple flange tips are too soft (Mee Pinnacle) while the remaining multi-flanged tips are RHA (bi-flange) or Spin Fit (bi-flange). These either don't get a great seal for me (RHA) or are a bit stiff and hurt my ears (Spin Fit), while other tips (foamies, single flange etc,) just do not work for my ear canal, so I've been trying to figure out a way to get the Shure triple flange tips to work. I was able to stretch the stalk over the bore of my U18t, but it's a hassle and, more worryingly, once on, it seems to shut down the sound and ends up creating a very boomy sound signature - I think the sound is being channeled through a narrow bore and getting mixed up and incoherent, I'm sure there's a scientific explanation but whatever happens, it sounds a bit muffled so I needed to widen it somehow. (By the way, I'm pretty sure this would work with Etymotic tips, but I don't have any to test it on.)
My original idea was to insert a soldering iron tip into the bore, but it ended up being a bit too hot. It either melted the core or it warped the tips
I gave up for a while, but after a couple of weeks I began to wonder if there was another way. So this morning, I grabbed a new pair of tips and tried this:
Firstly - cut the stalk to a length you need. I usually cut it to within 2mm of the line of the bottom (base) flange.
Next - grab a solid rod that's a mm or 2 wider than the current hole. A tapering point works best. I used a couple of soldering tips for this - the one on the right I used for the bore of the stalk (it's narrower and therefore grips the IEM core a lot better) and I used the one on the right for the end from which the sound is emitted. (Example pics in the three pics below)
For each insertion, boil some hot water and place the tips while they're stretched out over whatever object you're able to find to perform this process into a small glass or dish and pour the hot water over it. Leave it for 30-60 seconds, then remove and pour cold water over it. You can then remove the tip from the metal rod and perform the same steps again for the other side (once for the stalk side, once for the audio out side)
Once you've done all four holes, you should be able to slip these over a pair of 64 Audio bore holes. I haven't tried this for my Solaris, but it should work just fine
Here are the results - alone and next to a standard tip which I have on my SE846.
Works wonderfully and it's really opened the sound back up to perform as well as (or better than, in my opinion) the stock tips, which I don't like because they keep falling out.
Anyway, hope this is of some use - I might have very odd shaped canals and therefore nobody else will need this, but if it helps just one person then that was worth my time posting this, I guess.