The basics of a surface grinder are not all that complicated. The "issue" is defining a set of specifications that would make for a good overall project. The size of the unit is fairly easily varied, but I would need good definition as to the resolution of (downfeed, mostly) such a unit. Laying out such a design is fairly trivial once the specifications are set.
How about: 6 inches (150 mm) vertical feed with .0005 inch (0.01 mm) nominal vertical feed resolution; 18 inches (450 mm) longitudinal table travel X 8 inches (200 mm) crossfeed table travel; with a ø1.250 inch (ø31.75 mm) wheel spindle as a baseline? Personally, I prefer a pneumatic longitudinal drive, but a cable-type drive is doable. What criteria would be appealing here?
Irrational minds want to know... ;-)