Working without a case

I have to put a PC in an awkward location (it has decent ventilation, but is L-shaped). I cannot find a case that works in the location I need to use so I am experimenting with mounting the computer on a piece of wood. Do I need the motherboard tray for grounding or other electrical benefits? Normally with everything in a case there is a metal cage around the components. I assume that if the case becomes charged that is a very bad thing for the user. However is there any electrical need to have the components mounted in a case?

I was planning to use a motherboard tray I salvaged from an old case, but the tray is too long. I need to either cut it shorter (which will likely leave a nasty edge) or ditch it altogether and just put the motherboard pegs into the wood. If I need the tray I will make sure all components or their mounting brackets have some contact with it. If I don't need it then I will put it out for recycling with the rest of that old case.

Thanks

Cablechewer