Just a shorter version of this thing: http://www.thingiverse.com/thing:1094614.
Requested by a few Thingiverse members, this version is shorter (and as such reduces print time and plastic usage), and has slight corner improvements to increase the removal friction, which of course, increases the insertion friction.
Designed using Sketchup Make 2015, and printed in PLA on a Makerbot Replicator 2 using Makerware 22.214.171.124 "Standard" Settings (.2mm layer height, 2 shells, 10% infill).
Print "Box.stl" and "Lid.stl". I highly suggest the build plate be precisely trammeled before printing, and not too "tight" (e.g. print head not too close to the build plate).
Test fit and trim, file, sand, etc. both parts as necessary for smooth insertion and removal of "Lid.stl" into "Box.stl". Depending on the colors you chose and your printer settings, more or less trimming, filing and/or sanding will be required.
Assemble as shown in "Assembly.skp" or "Assembly.stl".
Feel free to comment if you have questions.
Hope you like it!
You fail only when you decide to quit learning.