It is so easy, done it several times and it has worked with zero issue every time. What I do is this. Doing only one cavity at a time set heavy wire hook in cavity and carefully close mold making sure hook stays in place. once closed....while holding closed slowly start tapping it closed with rubber mallet. I think a vise would work best as long as you go slow but I have no vise and the tapping it closed has worked every time. I have done this with round head mold, pony head mold, ultra minnow mold, recessed eye socket round head mold. I only use the mustad 32833 for the most part so it was a no brainer to make these molds accept the hooks. I do sometimes need to use matzuo sickle hooks (small diameter shank). I take a dap of red high heat RTV and place in the grove...smooth out, let dry, then down center make a slice in RTV with razor blade. This allows the shank to fit tight with no flash when using on smaller diameter hook shank. I also use the RTV to fill in the area of the mold that forms the keeper for rubber baits/skirts so that I have a bare shank for tying. Super easy.