>>10032356As the name implies they are quite literally, kits but made out of resin, 99% of the time they come from small home operations/some boomers passion project (aka garage kits).
They look like pic related. They're more straight forward to build than plastic kits at the cost of slightly less durability (thin parts are prone to brittleness).
Their quality can vary GREATLY which is why reviews are super important for resin kits, it all comes down to how skilled/how much of a shit the guy producing the kit has/gives. Some are masterpieces, others are genuine pieces of shit not worth the money, hence why I am informing my fellow resin kit bros that I will take one for the team and check out MMK models who as far as I'm aware doesn't really have any reviews for their BMP kits online.