this is super easy mod, doesnt require any 3d printer, cutting, drilling etc etc. one just have to apply a nail polish to "thicken" the combiner port and grimlock's "shoe". Once done it is quite solid and will not fall off. the only downside is one will have to sacrifice 2 combiner bots for their ports in my case, i use wheeljack and smokescreen as i dont see them as a combiner at all, but it is not permanent as i can always revert back to original. enjoy the pics.