To get started, the many times I have started over, it was always handier to start with something to carry it all in. It is the container that makes it a kit.  
Good point Art.  I started with Doug's PSP.  Looked at trying to put it into an Altoid tin.  Realized I also had a few snares I wanted to add and looked at the OtterBox.  Found out the the OtterBox would hold two Altoid tins perfectly along with a mini tin.  The kit evolved from that.