Hi AJ - I think what you are trying to do is a tough call. I also studied part time and worked for various companies through that process for my degree. My suggestion is that you put the money into a good CAD system (or use a free one like FreeCAD) and create a relationship with a machining company. Learn to build good CAD models and drafting skills. Finding part work can be tough and then committing to building the part is even tougher with small machines. Great for a hobby but time and material and cheap machinery is not a good mix to make money. So your concept is the same except you will contract the parts. You do the model send it to the machinist for quote then talk to the client. If they accept the quote then the shop does the work. So in the end everything is the same except the result is better, you get paid for your time, you learn a lot. Also if the part requires laser work, machining or 3D printing no problem, use the shop that has the appropriate tools. Work on building up a network of machinists, painters, moulders whatever is needed. Then you should also pick a speciality area that attracts clients. When you market you need a hook and this is your speciality area. If you market for general work you will get all sorts of enquiries too many of which will be dead ends (read waste of time and therefore money) I now run two businesses for myself, one a consulting engineering business and I design machines (small high tech stuff through to very very large mining equipment) and 2) a cnc machine kit parts business. Both of which use contractors for making all the parts. I have done this for 30 years or so and it has become a successful way to do stuff. A good designer is one who designs stuff that although exciting and interesting is also doable. I see alot of stuff in machine shops that the machinist is complaining about or ignoring that is either tough to do (and could have been done much easier and the result would be the same) or is over specified or so many things that only time and experience will get you. So forge an alliance with a suitable company and become a great designer and project manager. Its an appreciated skill and resource when you can say you know how to get something done and then do it. When you do work for a company go and speak to the people on the floor and look at the machinery. Don't be an aloof engineer. They will give you more info then in any book and get your hands dirty on machines welders printers benders... whatever you can as much as possible.
If you do have a makers bent then you need to research machines very carefully. Machines make more money then people do (but can cost you your business) so always buy the best you can afford that does the job. If it does not do the job then don't buy it. For many years I dealt with manufacturers that spent alot of money on machines and I could not get my head around that they had fleets of engineers so why not make machines or whatever. Took me some time to learn about money vs time vs machinery. A machine has to make money, if its idle or still on paper its not making money. So also put on your list some business studies, that will do you some good as well.
Good Luck Peter