From PROBOTIX :: wiki
Making a New Spoil Board
The below file can be used for cutting your own spoil board sized for Probotix machines. All necessary mounting holes are present so any material you cut may be used as a drop-in replacement.
You may also want to use our sample files for cutting a grid on the new spoil board
Installing/Removing the Spoilboard
It helps to use M5 studs to hold the t-nuts in during removal or reinstallation of the spoil board. You can cut the heads off of longer M5 screws, if you cannot find M5 studs. The studs will also work as alignment pins during reinstallation.