Reactor Rubber (formerly Kaysers Novelty), now out of business, made a beautiful, easy to walk in hoof boot for ponyplay. I am fortunate enough to own a knee length version of this boot in black leather. The pony boot from Reactor Rubber is probably most well known for its distinctive, realistic hoof shaped bottom portion. Reactor hoof boots have been (and still are) featured in many ponygirl videos and photos.
These hoof boots do very occasionally come up for auction on eBay. I do check the auction listings fairly regularly and post links to ponyplay related products on eBay. Moreover, some sites featuring ponygirls will sell their older equipment on occasion, and sometimes these sales include Reactor hoof boots. One notable example is Pet and Ponygirls, which has sold an old pair of Reactor boots in the past. Also, I know of at least one pair that go sold via a forum posting in one of the Fetlife pony play groups. Also, rest assured, that if I become aware of a pair of these boots for sale, I will post more information and a link on my homepage.
The Reactor hoof boots are less "bondage" type boots than the Punitive Shoes Pony Boots: the Reactor boots are significantly easier to walk, and even jog or run, in. Moreover, the Reactor boots have an added piece of metal welded to the attached horseshoe to aid in balance (see photo on the top right - the Reactor boot (bottom pane) and the Punitive (top pane)).
Of course, you can always change out the horseshoe on the bottom of the boot if you don't want to make use of this feature. To do this, you will only need a screwdriver and a new horseshoe. If you change out the included horseshoe for a standard (without welded attachment) horseshoe, it will be more difficult to balance in the boots though still not as challenging as the Punitive hoof boots (the lacing and angle of the Punitive boots makes them intrinsically more difficult to balance in).
One of my favorite features of the Reactor boot is the hoof portion. Unlike many of the other hoof boots available, the Reactor hoof boot does not terminate in a standard boot or toe bottom. Rather, the Reactor boot has a hoof shaped enclosure, which encapsulates the bottom portion of the boot. The hoof shaped enclosure is simply a couple pieces of thin metal welded together in the shape of a horse hoof. Leather is coated around this hoof portion to give it a cleaner, more aesthically pleasing look.
The overall result is a much more realistic looking bottom (see photo above left comparing the bottom portion of Reactor hoof boot to an actual horse's hoof). In principle, the hoof shaped bottoms should be fairly easy to make, but I have never really tried to do this. Given the end of production of these boots (and the overall end of Reactor Rubber itself), there is likely a market here for those who wish to design a boot with a similar, realistically shaped hoof bottom (I am aware that a couple people that have made similar bottoms as one off or custom work - there is one person on Fetlife that has done something like this, but I don't have website to direct you to unfortunately).
Well, they look realistic; they're comfortable to walk in; they sound uncannily like horse hooves. However, if I have to say something bad about them, it is that they're too comfortable to wear. For sure, these hoof boots are great for longer sessions, or for trotting and even to go over small jumps, but there are times when I want to have difficulty walking in my hoof boots. I very much enjoy the BDSM aspects of pony play, and sometimes I want to feel restricted by the trappings of pony role. For those sessions, I choose the Punitive Derby boots. Nevertheless, the Reactor boots are almost always my first choice, and with only one exception, are the only boots I have used in photo shoots.