perhaps a small umbrella ?
Since the switches aren't mounted to the board yet (as best I can tell)...
...can you...
1) stack the switches one on top of another , then put one covering over all?
Some kind of deep-dish tupperware, maybe?
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2) varnish the board, screw the switches down in-place as shown, and put an upside down tupperware container over each?
Notching the edges of each for cables, of course.
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3) saran-wrap the whole thing, put in a breather hole or soda straw, then put the sand bag back in place?
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4) add two inch "sides" to the board, then fill the whole thing with 2" of potting material
The silicone kind, not potting soil. ...though....
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5) I really liked the "under the table" idea promoted above. Are your cables long enough?
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6) spray the whole thing with some sort of water-proofing goop, and forget about it?
That's all I got. Anyone else?