I also built a 16X20 print washer along the lines of the Zone VI washer about 15 years ago. I still use it today along with a Zone VI that I bought used about 2 years ago. I used 1/4 inch acrylic for the walls on the one that I built. The Zone VI that I bought has 1/2 inch walls. Much more substantial. I wouldn't hesitate to build one again. Acrylic can be cut with a table saw. The necessary holes can be drilled. The gluing is straightforward.