If you are worried that your structure is too big to support itself and might end up moving or bending, you have a few options to prevent that - one of which is using plastic rivets. While gluing is another solid solution, the plastic rivets allow for the stabilising of a structure as well as the possibility of disassembling the structure in the future.
Small structures are able to maintain their own stability because the pipes are never far from a fitting, but larger structures often have pipe go on for a while without a fitting to stabilise it, and so risk moving around and out of the shape that you want it to retain. Gluing your fittings and pipe makes for a really strong, sturdy structure; however, our plastic rivets do the same job, while also offering the possibility to dismantle your structure and move it or change it.
To use these rivets, you need to first assemble the section the way you want it. Slide your pipe into the fitting, and give the fitting a tap with a wooden mallet - not a metal mallet - to ensure the pipe has gone down all the way to the stop inside the fitting. The formula of the furniture grade PVC pipe and fittings is designed to take impact, so don't be worried you'll break anything with the wooden mallet. Next, take a 3mm drill bit and drill through the fitting wall and the pipe wall as well - make sure you don't hit the opposite wall! Separate your plastic rivet by removing the top piece from inside the bottom, and push the bottom piece into the hole you have drilled. It might feel a little lose, but that will be fixed when you push the top part of the rivet into the bottom part as, once you feel a pop, the top piece will expand the bottom piece and lock it in place. Once the bottom piece is flared out like this, the only way you can remove the rivet is by first taking out the top piece.
When the rivet has been pushed into the fitting, the only evidence of its presence is a small, white dome - nothing ugly or obnoxious! However, if you want your fitting to be as smooth and unblemished as possible, you can drill the hole around the back or the underside of the fitting, somewhere that will not be visible to anyone looking at the structure.