Making the mounting brackets for most caliper installations really isn't magic. There are only a couple of basic dimensions needed to get the unit positioned over the rotor correctly. Determining those dimensions is easy if you have the parts on hand to mock up and measure. Depending on the specific application (vehicle's spindle/mounting ears, caliper shape, rotor size), the bracket might be fairly simple or it could be rather convoluted in shape. The ones that work out to be more basic can be made without the need for elaborate equipment. It's the ones that are very complex in dimension that might require more specialized machines to fabricate. Frankly those combinations are likely not the best options to use anyway, for other reasons. So I guess the hardest part is having access to the calipers in consideration to do some trial fitting; if it works out then everything's fine, but if not then you have a set of calipers you can't use.