Crius cross, Crius square

See what I've done? For PVC structures the Tee is the expensive part and the most restrictive part. Now I can get rid of it in many circumstances.

Say if you want to pack a lot of pipes close together to form a raft like structure. It's not possible with Tee's because of the minimum distance between two pipes. Now you can pack two pipes side by side close to about two PVC pipe wall thickness.

Say if you build a pet cage out of pure PVC pipes. Now you just need a outer frame with rigid Tee's. The "walls" of the cage can be lined with pipes secured by Crius crosses.

Unlike Tee's, now it is not limited to PVC. You can use EMT or PEX for environmental friendliness. And since they are designed to be incompatible with different diameters, so for us there's always something to clip it secure.

Sometimes one clip is not secure enough for the pipe diameter, especially using the Crius cross. You can use concentric Crius clips - the Crius square.

By varying the arc length, it can be very hard to take off the clip unless slipping it sideways. On the other hand, using two clips side by side make it harder to slip sideways.

And if you apply some glue, it's not possible to take them out in many cases.