I think a lot of people are trying to make a Mac Mini given it's possible now to buy new hardware which is 2x or 3x as fast as the 2012 mini for the same cost as a much sought after used one.
You will end up needing a WiFi card since those have bluetooth on it and you need that for handoff, some features I believe require a BT hardware MAC address to exist, and most importantly for a BT mouse or keyboard which you will end up using.
First you'll likely try to get a mini ITX board and fit it in a mac mini sized case, the problem with that is the best WiFi cards are PCI express and the ITX are expensive, limited with usb ports and the small cases they go in are expensive too. You'll find out bigger boards are cheaper than ITX and that bigger cases are cheaper and can include a standard PSU, rather than pay a fortune for the pico usb and its power brick and spend ages calculating power requirements. Then you'll realise you have more ram slots so will end up building a more powerful machine and just getting a high spec quad core CPU because you saved money on the board and case. Then once you look into higher spec you'll learn about M.2 drives and try to find a port with one of those slots so you can take advantage of the newer SSDs and reduce your internal wiring.
Overall I think a mac mini style is a cool idea but it's must more cost effective to build a bigger machine at the moment, just hide it under your desk if it's ugly.
For me, having done some research into hackintoshes again after a couple year break, is the setup process is still laborious, if you watch some of the guides on youtube it takes hours, and very tedious including entering serial numbers of RAM as well as hitting some problem or another. Even if you do make it all the way through you still end up with a machine that can't wake from sleep, although that's more Intel's fault than hackintosh given real MacBook Pros with Intel graphics can suffer the same problem when using external monitors.
One thing that would really help is some pre-configured OS images for some mac mini configs, although there are many pros and cons of that, the main thing being when something goes wrong it's harder to fix if you haven't been through the set up yourself.
