Based on drawings from Da Vinci's Codex Atlanticus, this Pathfinders catapult kit uses a pair of bent wooden arms as springs to launch clay balls (included) over (4) meters at enemy fortifications (not included, go make your own enemies). The assembled model will be approx 9" tall on a 10" x 7-1/4" base. Made from pre-cut, untreated wood from sustainable forests, and built with pegs for added strength and verisimilitude. A 2013 Creative Child Magazine Top Toy of the Year Winner and a great resource for STEM activities. For ages 12 and up.

Could be a new line of cologne, but in fact, it’s a clever kinetic action demo kit called Wave Wires® with magnets marked for polarity, and mounted on (4) 8-1/2” long wires attached to a 4-1/4” square steel base. Includes a dozen 1/2” dia steel disc weights, an acrylic ring and an 8-page activity booklet. The attraction/repulsion magnetic properties cause the magnets to swing on top of the wires like old-time circus acrobats. Ages 8-14. Really cool, if we don’t say so ourselves.

Everything you need to build a little DC motor is included in this kit (except sandpaper, screwdriver, scissors and, of course, an AA battery). The instructions are simple and explain the theory as well as assembly. Fun and educational for ages 12 and up.

Physics faculty alert: It's very small, but teaches a powerful lesson, this little diamagnetic-properties demo kit. You get (4) plated magnets, each 1/4" square x 3/32", and (2) 1/4" square pieces of graphite to float above them. The graphite may have slight chips along the edge but that won't affect the effect. Includes instructions/fact sheet.

It's small, as actual solar systems go, and you have to assemble it, but still…. You snap together this (not-to-scale) model of our solar system, paint it, and position the pieces. You get (6) colors plus a tube of glow-in-the-dark paint and a brush, the (8) planets (Pluto didn't make the cut, remember), and cardboard rings for Saturn. Sizes range from just under 1/2" for Mercury to the 1-7/16" sun. The finished model is articulated and stands approx 4" tall x 12" across on a 3-7/8" dia gray plastic base. Ages 8+.

From Fascinations®, these small model kits are made from intricately laser-cut polished steel. Punch the pieces out from the 4-1/4" square sheet and put them together with the tiny tabs. You pick the dragonfly, with a 4-1/2" wingspan or the Black Pearl pirate ship, approx 3-1/2" long. For ages 14+, because they take plenty of small motor skills.

Home robotics, bubeleh. Build a working hydraulic arm with this excellent 66-piece kit from Pathfinders' Simple Machine series. Structure is die-cut plywood and the kit includes tubing, (3) syringes and glue. You'll need a ruler and scissors. The finished arm will be approx 13-1/2" tall and will reach out over 16" and rotate 90° on an 8-5/8' x 6-7/8" base. Comes with a 12-page manual and uses water. Beautiful, too. For ages 8+.

And teach a kid (8 and up) the basics of solar power. This excellent educational kit from Elenco comes with (9) 0.5VDC solar cells pre-wired in sets of (3) and mounted in a 5" x 4" x 7/16" black-plastic frame with screw terminals on the bottom. The kit includes a 1.5VDC motor with leads and a mount, a fan blade and (4) plastic discs from 5/8" dia to 2" dia for mounting on the motor shaft, a 1.5V incandescent bulb with leads, a sound module with leads, and graphic cards to mount on the discs. Comes with a 14-page instruction/experiment booklet, including info on increasing voltage and amperage, powering battery charges, radios, games, etc. Lots of science project potential. "Heuristic as all get-out," Jarvis said when he saw it. Ages 8+.

For the steady-handed model-maker. These mini-models from Metal Earth® are demanding and beautiful. Use a tweezers to punch out the little pieces from the laser-cut shiny steel sheets, and assemble them using the tabs and slots--no glue, no screws. You pick the Hubble Telescope (3” x 2” x 2-1/2”), the U.S.S. Arizona (5-3/4” long) or the 1908 Ford Model T (3-1/2” x 1-7/8” x 1-3/4”). All include instructions, which you’ll need. For ages 14+.

When ornithopters roamed the earth…oops, no, it just sounds like a dinosaur. The ornithopter was one of Leonardo's masterful designs, although this one just led to a bunch of guys on winged bicycles plummeting to the earth in the 19th century. Still extremely cool, however, in this kit version. Pre-cut, unpainted wooden pieces assemble with pegs to make a crank-operated moving model with a 24" wingspan, complete with a human figure, which our model-guru calls a 15th C. crash-test dummy. Ages 9+.