There are companies making atty's that work with 510 threads------ and are called 510's. I believe the original was JOYE 510. As far as I know, janty, joye, tornado are all identical, same manufacturerl, just different brand names---and there are others. I call that the "staple"----you know, like milk & bread--the staples.
I've heard many great things about the Riva---but techically it is a clone 510 ego as JOYE is not the manufacturer. I've got their pass thru and love it ----may be a different pass thru style than what you had----as it is essentially the same, but you can charge & vape at the same time.
There are several products available that fit 510 battery threads--some are JOYE and some aren't. There are different manufacturers as well as brand names. Your's is a very popular one, the Riva.
The way I get it, in search of better equipment & whatever not only did the Mod Era really take off -- some ECFers got their own line of atty's (and carto's) manufactured to offer some choices and to work toward the best vaping experience. As we are all different, that is a chore!
In any event, Ikenvape & Cisco are very well respected and sell 510's & other models. The lastest production run from Iken was all assembled here in the USA, with casings shipped here from in China. I think I read that Cisco got US components (better wire) and got them produced in China. I'm not sure if that fits into your idea of 3rd party---but I gave it a shot.
Also -- it seems to me that many Mods use 510 threads.
