My previous Instructable, a gumball machine fish tank, came out nicely, but had a few problems. One was the need for it to be on a stand, and another was how unstable I felt the bowl was on the base. I reworked my design and it feels much more solid now.
You will need:
Gumball machine: I prefer round, glass globes, but it's up to you.
1/4" thick glass, cut to size, with polished edges
Aquarium sealant. Regular caulk may contain chemicals harmful to fish! Don't use it.
Small tank filter
Colored glass marbles (optional)
Assorted threaded rods and nuts
Foam (for noise dampening
Rubber grommets (assorted sizes)
Jigsaw (or a lot of patience with the hacksaw)
Razor blade (for trimming dried sealant)
Step 1: Disassemble and Clean
Simple enough; take the whole machine apart and clean it.
Step 2: Paint inside of lid
One of my mistakes on the first iteration was not painting the inside of the steel lid with a rust-proof paint from the start. This resulted in water splashing and rusting the bare metal, then dripping down and poisoning the fish. I painted the inside of the lid and the retaining ring with rust-o-leum white rustproof paint after all the drilling and cutting.
Step 3: Seal the bowl
The ~6-liter bowl has a 5 inch diameter hole at either end. Last time I sealed it with a single 5" glass disc on the outside of the bottom. I was never happy with this, as I worried that the silicone could one day crack and the bottom would fall off. It also elevated the bowl another 1/4" above the base, giving it a look that I felt was awkward. I remedied this by having a 1/4" thick by 5" diameter glass disc cut, and then sliced down the middle, giving me two half-circles. I could then lower these INSIDE the bowl, and seal them together on the inside.