Cait, That That, these are wonderful ideas, I may even explore. I have been looking for something like that. I think the closest to those pony trainers I ever saw was on insex or something, where a chain was wrapped under the heel and around the ankle, looked kind of painful and bulky though.
But I think what makes the original idea so interesting is the invisibility of it. I mean, if you are walking miles down the street, where heels are totally impractical, but you really don't have a choice, as the shoes are the easier route. Someone, out of concern, asks why you don't kick off those awful shoes, you are forced to either tell them to leave you alone, or confess to being bound so close to your bathing suit area, which could lead to a free soft core pornographic display of showing it. Or just suffer silently, possibly in tears. You don't really want to hitch hike, right, a shortcut to the keys?
Or think of the "Chore Whore" who is running errands all over town, in towering heels. Standing in line, you get a phone call from the person tasking you to run the errands. After the calls, the person standing behind you figures out that you are "paid" to grocery shop, but asks why you are in 6 inch heels. Write your own explanation here, but the fact is, you can't even stretch that high in your barefeet, as it is no longer about height, because you can only get that high by rolling the ball of your foot forward.
If I grab those ponies, I'll let you know. $$ is the biggest obstacle right now though, have to watch my $$ until I have a good lead on my renovations here. Maybe I'll DIY a set, the mechanics seem simple enough. Don't know about making them at all comfortable.
Thanx again friends. Shan' salutes you

Bondage is like a foreign film without subtitles. Only through sharing and practice can we hope to understand.
A Jedi uses bondage for knowledge and defense, never for attack.
I am so smart! I am so smart! S-M-R-T!....I, I mean S-M-A-R-T!