We bought a portable cryostat in one reference lab where I worked so we could take our frozen show on the road but it was so small that even I, with short thin arms and small hands had trouble working with the tissue in the box. We returned it. Actually it had other problems too. I hesitate to mention the brand name but if you email off the net I'll tell you.
Just this word of caution - before you buy (these things ain't cheap!) make sure you try it out to see if it "fits".
Andi