The standard Arduino board only allows 2 motors as it has limited I/O (please correct me if I'm repeating wrong info here). So, how would I go about controlling 4 motors easily?
Also, can someone recommend motors for this sort of thing? They obviously need to be strong enough to lift the weight of this thing. I'd like substantially more power than I need too, if possible (would be nice to carry light objects).
Lastly, what about tools? Would I require a soldering kit (iron, solder reel, sponge, etc)?
Apologies if these things seem obvious, and thanks in advance.
I have a few thoughts on your "learning experience" - I think it is awesome that you are going out and building your own quad, as it is a very rewarding, albeit frustrating process. You will learn more than you had ever wanted. With that said, it seems that you may be lacking a significant amount of important information for your project to be successful, or I am just misunderstanding your post. Most quads run brushless motors with low kV, which require their own ESCs (speed controls). These run from a pwm signal, and the basic arduino has six pwm pins, so your limit for motors is six, or 4 motors and 2 servos for camera stabilization. So while the basic arduino has limited i/o, there is certainly enough for the task at hand with some left over for you to play around with.
Here is a website with a project similar to what you are trying to accomplish, and the documentation is quite good: http://www.scoutuav.com/2011/12/13/low-cost-arduino-based-auto-stabilizing-system/
There are many setups online for motors/hardware for your quad - you must first set a realistic target weight and then choose your power accordingly. Common setups have 18-30amp escs, 3-4s lipo batteries, 10-12" propellers, 700-1500kV brushless outrunner motors, and 6-9 channel radio setups. Even if you buy the stuff from hobbyking or another Chinese retailer, it will cost you a good chunk of money. Add to that a good soldering iron (those 10 gauge wires on the batteries can be a pain in the butt to solder) and
*I know this is probably not an answer you were looking for, but I would seriously recommend getting an arducopter board/platform and getting something in the air at first, before getting frustrated with doing everything by yourself. It will be QUITE the learning experience, even without looking at any code. After you have something in the air, you can mess with code and whatnot.*
I hope this reply was helpful in the least bit, and I can elaborate once you throw more details of your plans - there is no "setup/motor" for a quad, but there re some very good ones out there. I am sure others can chime in as well.
*edit - looks like while I was typing 5 people beat me to the punch. Awesome bunch here on these forums!