Good news and bad news
1st the bad news: What they were using were prototypes that were made by cutting down Step Company steps. There was a big push after the PS series came out to encourage Step Co. to start making them, but Step Co. declined. So there is no retail source for those nifty little mini step toppers.
Now the good news: There are directions available on how to make them on my web site and here's a link:
http://www.avalon.net/~ferragut/MiniStep/
These were a product of the work of another Cathe fan and myself who were determined to have one of these and, each unbeknownst to the other, began designing and building one. She finished hers 1st and posted her directions. I was floored at how similar they were. We had most of the same basic ideas, just a few different materials. I took what I considered the best of both designs and put them together and made the 1st draft of the directions. Over time as I distributed them to people who asked about them, I started getting feedback on how other people solved problems or different materials they tried, plus I made a few more myself, and the current version of the instructions came to be.
I wasn't going to post about this here because I didn't want to seem mercenary or anything, but since you're asking specifically . . . I made another mini step topper last week ( my 6th :-wow )and listed it at Ebay yesterday. Here is a link:
http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=1802846128
I didn't put a reserve on it because I didn't know what a fair price would be for it. I chose to let the "market" decide.
I hope this info was helpful to you. Good luck!
Erin