Art Applewhite
Now for something completely different, the Helix
(Not recommended for beginners)
24 mm Helix - $20 each
Recommended motors - D11-P, D12-0, D12-3, E9-P, E9-0, E9-2, E9-4
18 mm Helix - $15 each
Recommended motors - A8-3, B6-0, B6-2, B6-4, C6-0, C6-3, C6-5
13 mm Helix - $10 each
Recommended motors - A3-4T, A10-0T, A10-3T, A10-PT

Top to bottom 13mm, 18mm & 24mm Helix
These rockets require a specialized launch pad (see below) consisting of a strong base and a short 1/4" rod or bolt.  Detailed plans for a low-cost pad using readily available materials is included with each kit.

Plans for DIY Monocopter Launch Pad

The launch pad for monocopter should be sturdy and fixed firmly to the ground. Never attempt to launch the Helix from a standard launch pad with a long launch rod.  A suitable launch pad can be constructed from the following materials:

Drill a 1/4 hole in the middle of one of the short 2x4s. Insert the carriage bolt into the hole and secure it tightly with one of the nuts. Attach the long 2x4, perpendicular to the bottom of the short one with two wood screws. Attach the two remaining short 2x4s to the opposite ends of the bottom of the first short 2x4 with two wood screws each.  Thread the two remaining 1/4-20 nuts on the bolt and use them to adjust the height of the rocket above the pad.
Monocopter Launch Pad
13 mm Helix - Recommended motors A3-4T, A10-0T, A10-3T, A10-PT