What style of frame would suit?
It is a matter of personal choice of course, but since I am frequently asked by purchasers and collectors I will offer my opinion and preference for your consideration.
For mezzotints, drawings and etchings I tend to choose a simple and relatively narrow "moulding" (moulding is the name given to the wooden frame and its profile or cross section shape - see lower right illustration).
I also select a pale wood and stain or lightly paint it white. I then wax it so that the grain and the tone of the wood are still just visible. This renders the finish as a slightly off white. I know that an almost black stain is also popular. I'd be fine using this for etchings but possibly not for the already very dark mezzotints....but thats my opinion.
Using conservation tape hinges, I then mount the artwork onto an acid free backing board. The backing board should be of a similar tone and colour to the paper of the artwork. It should also be about two or three centimeters larger all round.
I then insert a slip into the frame after the glass is in place The slip is the same width as, or less than the lip of the moulding. It is several millimeters deep and forms a shallow box frame, keeping the artwork away from the inside surface of the glass (vital for conservation reasons, preventing possible condensation from being absorbed by the artwork). Never use non reflective glass as it is textured and can harbour damaging moisture.
The completed frame allows the whole paper object to hang inside the shallow box with the natural deckle or torn edges visible as clearly seen in the photograph below.