you could join the panels using the plastic weld glue used to create wc reservoirs
below taken from http://www.bit-tech.net/modding/guides/2010/02/28/how-to-make-your-own-watercooling-reservoir/2
The best stuff for solvent welding the ends on is either IPS Weld-On #3, or TAP Acrylic cement (which are effectively the same thing) from tapplastics.com. A 4oz jar will do several reservoirs so itâ€™s an investment or provides a lot of practice. You also want to get the needle type gauge applicator (16 gauge hypodermic). The needle applicator gives you excellent control of how much solvent you use, whereas the bottles donâ€™t at all and you'll get solvent everywhere if you use them.
While you are there shopping, if you solvent weld acrylic for other purposes, you can pick up a tube of IPS Weld-On #16. It is a lot thicker and is handy for gluing together acrylic in general, but for this particular purpose, it leaves far too many bubbles in the seam that can leak fluid. If properly used, this solvent weld will hold all day long at 10 times the pressure that we have in our watercooling systems.
In order to get solvent from one end to the other, I use a piece of small brass tubing that I bought locally for about a $1 at an ACE hardware store. The end was bent to make it easier to get into the bottom seams.