Hanging a HDPE Shelf

[rsumner]

I bought a 2ft x 1ft sheet of 1/2" black HDPE on Amazon so I could hang a shelf in the wet area of my sump cabinet. The goal is to put my Neptune Trident on it, so it doesn't really need to be more than 5"x12". Any ideas on how to attach the shelf securely to the wall of my sump cabinet?

I was thinking about something like these would work since I went with 1/2" HDPE: Amazon product ASIN B08FLZBXFY
The Trident doesn't weight much (even with full reagent bottles), so I'm hoping something as basic as these L-Brackets would be enough.

I was thinking I could even do the same to build a U-shaped shelf that could hang from the ceiling of my sump cabinet to hold a Kamoer FX-STP pump.

Thoughts/concerns?

 

[Gtinnel]

Assuming the shelf is just mounting on one side I'd probably go with a slightly bigger bracket. Something similar to this

If you or someone you know has a 3d printer there is a bracket specifically for the trident