For these I used the Maroske style fitting. I used the instructions on Bjorn Thomasson’s site but in retrospect would do things a little differently.
The first couple that I did I left the pvc tubes in place for more than 24 hours and had a tough time pulling the tube out. In the end I found a hair dryer would blow in hot air and soften the tube sufficiently they came out. For the rest I found if I just pulled the tube out within 12 hours I was fine.
If I was doing it again I’d put a few larger pieces under the pvc loop then cover the pvc with epoxy mixed with lots of chopped up fibreglass then place a couple of larger pieces of glass over the top. I’m sure it would make a smaller, better fitting.