Continuing with the ASHPD - It is coming along about as expected. Today I used the cut outs of some of my flashcards to mold the final part of the edge between the 3'' and 4'' pieces. I was going to use superglue but discovered that the superglue that I had was all dried up so I ended up using a hot glue gun. Glued those pieces on, each has a width of 1/2" and put the spackle in between. Then filled in a bit and set it aside to dry.
The next step was using the hack saw to saw off the ends of the acrylic plunger handle. It was a lot easier than I expected it to be, didn't take particularly long. If you do it in a circumferential fashion you can just break the pieces apart when you've done enough. Then I took some of the sandpaper (100 grit for purpose of records) and sanded it outside for a bit - again, didn't take too long. There's still a line that I couldn't quite get sanded because of how it's manufactured, but that part can just be face down. See the updated pictures below!
I think I will end up using the telescoping portion of the tube, on account of the thickness of the device I'm making isn't all that thick. I could work on the front nozzle today, but...alas, studying and eating await.