You can certainly get some nice versions of this from online fetish stores, but if you want to save some money or you just like to make things yourself, this is a project that doesn’t take much material or special skills. The ponygirl bit gag would look just as great on a ponyboy as it would on a ponygirl, and bit gags are actually great in BDSM even if you’re not into pony play.
Bit gags, in general, aren’t a comfortable gag, but if you’re a bit of a sadist then that might be just what you are looking for. The addition of the nerf ball to this design might actually help it be more comfortable for longer term wear.
The BDSM Glossary group on Fetlife defines a ponyboy or ponygirl as:
A submissive dressed in a harness, often very decorative, usually with a bit gag and a butt plug with a tail. Often they will pull their Dominants in a cart. Meetings and competitions are held for fanciers of this play.