3 letters:
hub, hud, hug, hum, hun, hut

4 letters:
buch, duch, hach, huck, huff, hugg, huhn, hull, humm, hung, hunn, hupp, hush, huss, hutt, kuch, much, ruch, such, tuch, zuch, huch

5 letters:
buche, dutch, futch, hatch, hauch, hitch, hooch, hough, hucke, hunch, hyche, kutch, mutch, sutch, szuch, touch

6 letters:
butsch, kutsch, mutsch