These etching tank plans were based on my requirement to etch parts for my miniature traction engine. However, this tank works great etching parts up to 100 x 75mm (~4 x 3 inches). Notes along with hints and tips on etching are available on this site.
The etching tank plans show the dimensions of the tank, how to lay this out on a single sheet of perspex/acrylic (A4 210 x 297mm and 6mm thick). This is readily available from a number of suppliers online. The plans would also work with 4mm, 5mm and up to 1/4 inch thick perspex or acrylic.
The tank has a small chamber at one end where a fish tank air supply is used to move fluid around the main chamber. The baffle helps to reduce the amount of bubbles impacting the part being etched.
The following video gives an overview of the etching tank and how I use it. It also shows how the fluid circulation works by adding some dye to a water filled tank.
Once you pay for the plans you will be able to download them via the link on the confirmation page, any issues let me know (firstname.lastname@example.org) and I will email them to you via email.