I am currently building a ATS and I am trying to replicate your build quality as much as possible while changing dimensions just a little. I already had the heatsinks, LED's, Acrylic, and of course PVC (Adult Lego's). My question is for the Tapping of the acrylic for the threaded holes on the input and drain holes. What is the size and where did you get tap & die (specifically the bottom drain) which I think from the videos is 1 1/4 pvc. The input seems to be 3/4 correct. Lastly what type of union are you using on the spray/drip bar that you can just screw in and out the compression fitting. I hope you understand imitation is the sincerest form of flattery.
The bottom drain is 1-1/4" hole with a 1-1/4" threaded to 1-1/2" slip adapter The side hole is a 1-1/2" hole with 1-1/2 T -> 1-1/4" S adapter The slot pipe holes are 3/4" I got the taps at Enco, they're not cheap if you are looking for single-use. Add in the tap wrench, which is a biggie, and only is good for up through 1-1/4". The 1.5" I use vie grips. Getting the hole the right size and then starting the bit plumb is by far the trickiest part. If the hole is too small, you'll never be able to tap it. Tapping the holes was the biggest improvement, IMO, that I made, but it also became the biggest pain in the $#@. Not sure what you are asking regarding the union?