Here is the jig I made for accurately drilling contiboard.
I just took these pics with a cheap poor quality digital cam.
The drill holes are exactly centred in the channel which is 15mm wide for melamine chipboard.
The drilling bush holes start exactly 1½" (38.1mm) from the square end and are the same distance apart to work with standard melamine chipboard sizes which go up in 3" widths.
The jig is 18" long so it can be laid on the board from both ends to take up to 36" wide boards
Top view showing bush holes and 3 drill bushes (8mm)
Under view showing channel
Underview showing one channel side removed for corner drilling
I've been using this jig since 1988 for making anything out of contiboard.
It uses 2 size bushes 3/16" for No8 screw clearance & 8mm for plastic chipboard plug (no longer made) or dowels.
The bushes can be moved in seconds to accomodate different board widths.
A new jig will be made the same design but with the channel width for use on 25mm par timber (approx 22mm)
It will need more care making by hand as the original was made on a vertical milling machine at work which I no longer have access to.