Where do I find a front tow cap cover?

Paint the toe hook see glass green and leave it in looks like a windup for a toy car. Seriously though other than off of a sea glass green in the junkyard or eBay looking for such and they're going to probably make you buy the whole front bumper cover so you have to buy a black one and paint it yeah I know sucks

 

I bought a pair of black ones on Ebay for $6. As long as they match I think it’s kosher.
Or you might inquire at a vinyl sign shop to match the color.

 

Just buy the matching paint in the smallest spray can you can get on Amazon for that sea green or whatever you call it and just shoot it right on a piece of wood in the carport two quick passes should be good to go never notice it I think this is part of the front bumper cover and you'll play hell finding it separately and any kind of colors black only probably

 

On 3rd Gen those caps were on pretty securely (in comparison, 4th Gen’s were getting knocked off in car washes). For whatever reason, since yours has proven capable of coming off, maybe put a dab or two of something, say silicone caulk, to hold it more securely, but still allow removal with some effort.