Waaaaay back when, I was too cheap to buy a Firm box
so had my husband (a carpenter) copy the exact design and make - and decorate with watercolors - our own 'Firm' box. It's 7" tall and I love it and still use it today. (You can see it under my profile.)
I used a step stool for the tall box but even that was a little too high for me. Now I use the High Step (at 12") but I *still* love using my wooden 7" box for Firm step cardio.
And yes, I agree that the original Firm equipment was built to last. I've begun using classic Firms again and am already getting compliments!