This is something I came up with to make reballing the interposers a little easier.
Should fit most top sections of these reball jigs, might need slight massaging with a vile and/or sandpaper.
this is for 1.6mm thickness pcbs, you could also fit pcbs in there that already have passives soldered onto them.
incase you have to try and salvage a failed attempt at the mod.
Xbox cpu interposer jig v5.stl