Superglue to a thin metal sheet, 3mm Aluminium is good, clamp the sheet down and when you've finished flip the work and heat the back of the sheet to break the superglue bond.
Mitre-Bond from Wickes is good as it's activated and reaches full strength really quickly, I use it to hold all manner of materials down to aluminium plates, you can "kiss" it with your cutter too without any worries at wood routing speeds,
Regards,
Nick