make your own
start with a 1 inch thick alu plate
.125 slotx.275deep around the edge(.125 inside the 7x7)
buy retangluar gasket from vac-u-form .125x.3125 rockford il. about 50 bucks
brush or cut pattern in inside area for vacuum
add vacuum (side or bottom)from a cheap pump can be done with a...
if cutting on a cnc,use a canned peck cycle this will retract the tool as set by parametier. i.e. cut forward .020
retract .002. this will at least give short chips.a very high positive tool works best. good luck