My husband has every tool you can think of. The reason I want to get a kit is they have special molding to go around rounded corners (all of our walls have rounded corners). I guess we could just get the specialty stuff but get the rest of the stuff at home depot or lowes.
Little bit of sanding on the inside the corner molding will do the trick. If the hubby is good with his tools he could always make custom molding to maintain the round corners if that's what you desire.
I cheat. Though out the years I've made jigs for various cuts and scrolls , makes things a whole lot easier.
Kits are fine. Doing it yourselves is cheaper and there is the additional pride in saying "We created it on our own".
I've seen people do it with paint, stain and even fabric over plywood. Seen some dramatic effects.