Clip-on brackets allow for temporary support of light weight items. I am using them to support my tomato seedlings. The aluminum foil tray is tie-wrapped to the triangular brackets.

The brackets are sized for .625" thick fence, so you may need to modify them for thicker fence material.

I printed them in low res, 10% fill in makerware on my FF creator pro using ABS. I printed two brackets at once since I had sized them so that two would fit on one build plate.