You could hinge it to a slightly-undersized backer of 4-ply, and then float that off the surface of a solid background. Be very careful with the hinge paste, as notebook paper is notoriously poor quality, and might cockle with the slightest excess moisture. Glass spacers, of course.
Or, you could use a DCO (direct contact overlay) mount, unless direct contact would harm the letter. Press UV-filtering, abrasion-resistance treated, optically coated acrylic against it over a sturdy, padded background. No adhesive of any kind touches the letter. When it is appropriate, this is a visually impressive, completely reversible technique -- and among the easiest to construct. Do not use glass for DCO mounting, due to its poor thermal properties.
