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.

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 = varies with LED selection. However, if you use the Blacet supplied LEDs (he
uses a standard T1 size) and you do NOT use a LED holder then the hole is 1/8"
Obviously, if you decide to use the LED holders, the hole must be somewhat larger
(might vary with the holder). I bought some LED holders for T1 LEDs. I think they will
work / fit well with the Blacet LEDs, but they don't leave enough of the LED showing for
my personal taste. And they didn't fit my replacement LEDs very well (see next note).

I only used 1/2 of the Blacet supplied LEDs. I wanted 1/2 of mine to be red. So, I
ordered some "standard T1" LEDs to replace them. While the "standard" seems to
address the diameter, I did find the bodies to be somewhat different. My replacements
had a lip round the base that Johns did not. So, that would have effected how they fit
into the holder had I elected to use a holder. So, the concept is that standard is not
always exactly the same. So, have your parts before you drill.

The LED holes are the most difficult. They are difficult to get in an exact straight line.
Some people use a back stop on their drill press. I just relied on my good eye and a
center punch. Of course, all drilling should start with a smaller bit and work your way up.
I sometimes start with 1/8" but would start smaller for the holes that are only 1/8 inch for
the LEDs.

The Lumex LEDs that Paul uses require a 5/16 inch hole. Of course, they are too
big for the Miniwave.

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 Miniwave, 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. On the Miniwave you will want to use it to "rim" the front of the LED holes.
Therefore, no "silver" color shows around your LEDs from the edge of the hole.