For table top work where a track separation of 9-10 inches is preferable to the normal 24" separation required by the Spider Dolly.

If you own either the 3-Leg or 4-Leg Spider Dolly you already own the Mini Trolley.
3 Leg Mini Trolley
Disassemble the Spider by removing the through-bolts that connect the two plates and legs. You do not use either the top plate or the Spider Legs. Instead, you simply mount the wheel-arms directly to the Spider's bottom plate using the through holes labeled either "3-Leg" or "4 Leg" depending on whether you are using 3 or 4 wheels for the Mini Trolley.

Notice that in the top picture the 100mm cup is attached directly to the Spider's Plate. For 4-Leg owners, you can use the 100mm cup from the top of your DV Column. For 3-Leg owners, you will need to purchase this additional cup. For those requiring a Mitchell top or 150mm cup, these can be added by using a set of risers (bottom photo)  that attach to pre-drilled holes in the Spider's plate.

100mm cup -- $100
150mm cup and 3 risers -- $275
Mitchell top  and 3 risers -- $150
3-Leg Mini Trolley with 100mm cup

4 Leg Mini Trolley
4-Leg Mini Trolley with 150mm cup

Mini Trolley w/ 3 wheels and 100mm cup, if purchased separately --  $775