Get a piece of panelling, and lay out a design pattern for the holes you want to drill useing a ruler and sharpy. Pre drill the panelling and look to see if the design looks good and is nicely spaced. If it is align it to the area you want the holes drilled in and tape it solidly in place. Drill each hole out using the panelling piece as a template. Make sure all holes are drilled before removing the template by dropping a ten penny nail through each hole after you drill it. If you want to use the same pattern several times you can. Just align it over the next area you want holes. If you want to make a pattern that will last for multiple uses in the future lay it out on a piece of 1/8" thick Plexi-glass. Just don't make any mistakes and make sure you center punch each hole before you drill it.