Kerf angled slots into your 2x4 to hold each item in your tool set. I use a radial arm saw for this but any saw that can kerf the wood could be used I...
Here is an instructable about how to make a wrench organizer. I bought one of these once and liked it but have more than one wrench set to organize. I didn't feel like spending whatever these things cost for each of my wrench sets so I decided to make one. I like the ones I made better than the one I bought. Mine is more comfortable for me to use and is more flexible in how it works. See it standing up in the image below. Oh yeah these work great for storing files too.
Step 1: Assemble your materials
Get together a set of wrenches, or files that you want to keep together and organized. Lay them out how you wish them arranged. Now get a scrap piece of 2x4 wood that is long enough to cover your set you want to hold.