When I last bought the mini version of the PENCIL CASE from Dai Nagata via Ebay I also bought his CAT CASE puzzle which was his IPP competition puzzle back in 2003. The price was also USD 4,99 and I believe I still saw it available on Ebay.
Self-speaking there is not much of a difference being the mini version Dai used to sell via his witful.net homepage (which is currently not working). It still has the same disadvantages to the big sized wooden version which are size, material and missing second challenge on the rear side of the puzzle. Besides that the goal is still to put the 4 “Cats” into the given frame. I could solve this one challenge available in about 5 minutes time which consequently results in the same difficult rating than the PENCIL CASE --> 2 out of 10. In my last review I had the impression that the precision of the mini version is not perfect enabling me to find 3 other solutions for the PENCIL CASE, however, with the CAT CASE I could only find one solution and comparing it with the intended solution it was correct. Though the pieces lie a little bit different in the case.
My resume is also similar to last time. For the very cheap price it is certainly no mistake to buy it but still the original sized puzzle out of wood is preferable because you will most importantly have a second challenge on the rear which I could not judge here. I think this puzzle could be something for your vacation because the CD jewel case can easily be transported and is still fun to solve.