Hi Tom, just checked out your build thread, looks awesome!
(Sorry can't quote... not sure how this new (to me) fandangled quote system works yet)
Yes, one side is glued together. The other side opens so we can get our feet through - getting the foot through at the ankle area is the problem.
Although they do close-up pretty tightly, they will eventually slide apart, so I did end up putting a strip of velcro inside on the upper side, but not onlyto hold the shin together, but to hold the ribbed gasket in place - this also helps to hold the shin closed, and has been enough and has caused no issues.
I stuck the hook side of the velco to the shin, and the fuzzy side to the gasket. I leave the entire leg section as one piece now, and only need to pop open the very bottom of the shin at the ankle a bit to get my foot through.
Hope this helps