Alabama said:The best mineral feeders I have are the ones I made and were the cheapest too.
Take a plastic 55-gallon drum with all the lids on it and cut a hole in the side big enough for a cow to stick her head in. Hang it from a tree limb or a frame with some light chain. Then fill with mineral. Very little rain gets in and if you use a nimble limb it sort of acts like a spring so the cows don’t bust the chain.