Jack size = 3/8" Assumes you use the 1/4" 112A jack normally used on MOTM.
However, most all 1/4" jacks use a 3/8" hole.

On my Time Machine, I dedided to use a 16mm Alpha carbon pot for the Regen control
because it has a center detent. The appropriate sized hole for that appears to be about
17/64 or 9/32 inch. Unfortunately, I already had my much larger 3/8 inch hole drilled.
The answer was a rubber "O" ring. A #5 rubber "O" ring from the plumbing department
at Lowes fit just perfectly. Thanks to Dave Hylander for this great tip and for sending
me some of his so I could shop to find the right size.

Switch size = 1/4" - That fits the Blacet switch supplied with the kit or the MOTM style
handle replacement, if you go that route.

LED = The Lumex LEDs that Paul uses require a 5/16 inch hole.

I have some other tips in case this is your first panel drilling:

1. Center punch is required. I use the automatic one they sell at Sears for
   about $8 - $10.
2. Drill from the front always. You have a lot of edge cleaning to do on the exit side
   of a drilled hole. Better to have that on the back. I also cover the panel front with
   masking tape. You don't have to. But, be careful as scraps in your drill bit will
   rotate with the drill and scratch your panel front.
3. Put a chamfer on most of the holes using a bit much larger that the original hole.
   This cleans up the hole (see # 2). I put a VERY light one on the front if needed.
   Most of that is for the back since that is where your edges will need it.
4. Once you get a hole to the size you want, put a piece of tape over it before you
   move to the next larger bit. That way, you won't accidentally drill the switch hole
   out larger while drilling the pot holes. I have not made that mistake (I credit the
   tape). But, I know those who have.

For the touch up, go buy a "Sharpie" brand black permanent marker. This black marker
is almost a perfect match for the MOTM panels and can be used to fix any small nicks
or scratches.