Tarquinh:
DWP:I am looking to build new speakers and want to use ribbon tweeter as a supertweeter but what midrange drivers should i use??
I'm afraid it's not as simple as that. I suggest you look at some of the books on speaker design that are available before jumping in at the deep end. You'll also find there is a fair bit of software available, too.
The golden rule is that you should know what sound you want to achieve with your design before starting, as that affects everything from drivers through crossovers to cabinet design. You may be better off starting with a kit to see how each component works with the others.
Making speakers is simple, my cat can build some in an afternoon, blind folded.........