No, its not a good idea at all. If you're learning to build coils, you're gonna get shorts, and if you get a short on a 14500 with an RBA is game over battery.
Better to learn to make coils with a vv/vw device since it has some protection, such as a vamo, tesla, evic, SVD, or one of those types.
This x1000.
To add: Make absolutely certain that you can check the ohms of the coil you built... the iTaste V3 can do this, so no worries there. (as can most mods in that price range, actually.) Barring that, get an ohm reader.
Do your research on coils, and wicks, as they each all do react different. A micro coil with a cotton wick will act different than a regular coil on that same wick.
What kind of RBA are we looking at? Some are waaaaaaaaay more finicky than others. My AGA-T+ is awesome when it decides to cooperate and not have hot spots and all that, my IGO-L and my Phoenix are very much more forgiving, and operate 100% of the time without issues.
I just have to reiterate that jumping into the mech side of things without really knowing what your doing as yet with RBAs has the great potential for complete and utter disaster. Best case on a short, is you wreck your battery... and you WILL short when building RBAs... (at least at first)
I'm not saying to NEVER get an Mech, I'm just saying to get one once you have the tools and knowledge to use it correctly, and can build a good working coil.