I have a few "C" clamps,

but these are the only two I use... but only because I'm too lazy to swap them out.  If I ever need to move that tray, they'll be relegated to the archives.
These may be ok on metal,

however, I reckon if you want them to hold, they'd scar the bjesus out of wood

If your first cut is too short... Take the second cut from the longer end... LBD