Interesting.

I heard the viscosity of the mix is one of the larger hurdles.

My thought was to use bubble hash, heat pressed or ISO and dilute it, flavor it and fill the carts. Would do it with my own flower, not bulk bought stuff.

Also, the refillable carts I was looking at recommended to only use them once anyways. They are technically refillable since it’s a silicone seal, not a mechanical one.

The additives some companies use, and the long term affects of the approved ones still aren’t fully understood.

That's nuts, literally everyone I know hates 510s 😂 I know guys who would rather not smoke at all than hit a 510. I personally hate them because I don't like how they taste or smell, and I also feel like my lungs hurt after a couple days if I smoke it too much. They are discreet as fuck though and at least they're not just manufactured e-waste like the disposables are.