I went through two major rounds of aquascaping. The first round was an absolute nightmare since I was still trying to figure out what works.
I initially glued the large pieces together underwater in 27 gallon bins from Home Depot (the containers with the yellow lids which they sell for $8.98). I used DD Epoxy which was absolutely horrible since it polluted the water, set very slowly, and yielded a very weak bond even after a few hours of curing. I also used a bunch of super glue but that does not hold as well as expoxy.
For the second time around I used the Tropic Eden 3D moldable rock. That stuff works great since it sets very fast and does not pollute the water. I only used that for the larger and more important joints. For small joints I used superglue. I did most of the moldable rock/superglue outside the tank for short periods. I also applied moldable rocks directly inside the tank as well since it does not pollute the water. When using superglue to connect joints, super glue accelerator is very useful.
You can also jigsaw the rock pieces together first then reinforce key joints to be extra safe.
To cover up the moldable rock joints, I took small pieces of live rock and superglued them on top to hide the joints. This is why you can’t see any obvious joints on the rockscape.
https://premiumaquatics.com/product...5&_sid=6c1f15179&_ss=r&variant=47329650901234