The simple answer is Another board of many ping pong balls!
Although this is not completed yet, read on to find out why....
But to give you a head start I thought I would show you where I am at and give tips where I can.
This was inspired when The Much Larger Board of Many Ping-Pong Balls by DaShroom was featured on the main page of instructables.
The only problem I had, like many others who frequent this site is that I didn't have a laser cutter to hand, I do have a CNC that I but many years ago but that has a small bed so this would end up as a small scale replica, and one thing I don't do is small scale!
So rather than try and show this as a new idea I am trying to help make this available to the masses by showing some "alternative" short cuts and how to's.
I looked at various options, polycarbonate triple wall sheets because they are very light and quite rigid but the wrong stock size and then rather expensive once you get the correct size, the other issue here is if you try and use 25 or 35 mm polycarbonate to hold the LED's and act as a diffuser you end up with the light diffused only in the vertical strips. You would have to adjust your spread from 40 mm to around 10 mm. I called in to a local supplier and once I explained what I was doing they gave me some offcuts to experiment with. Very nice people and well worth a mention at Nick Gray Plastics if you need any sheets.
PCB sheets with the tracks cut in like they used on the Solderlab site, looked very expensive and I could not find a local supplier that did anything near big enough, I even looked at using small panels that could be bolted together, the problem there is stability once you assemble the unit, then it becomes too heavy with all of the stiffening bits in place.
The simple answer (for me) was a trip to B&Q and to buy one pack of end of line laminate flooring for just under £10, then use some flat softwood to build a frame. I used glue to assemble the base so it was good and solid then spent some time making a template for the holes. It is worth spending the time because if the template is wrong so is the finished article.
I used 5mm LED's so to give a clean hole I drilled everything through the template with a 4mm bit, then once they were all done I opened them up with a nice sharp 5mm bit. Its worth noting that I had to keep changing the bit because they went dull quite quickly. On the back side I used a standard countersink on each hole to ensure that the LED protruded from the front by around 4 - 5mm.