This is the way it would look after you glue the bottom pipe.
Next step is you're going to create a template out of mdf or whatever scrap of wood you got laying around that will fit inside the 4" pvc tube. Like so:
Use the jigsaw and cut a piece of acrylic slightly larger that the template of wood or MDF
Use double sided tape and affix both pieces together, now your will route your acrylic piece.
Drill lots of little holes with a 1/8" bit on the circle you just cut
