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.

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.

His name is Tobbie II, and although he stands only about 6-7/8” tall, he does sport (6) actual feet, which is why he has such an agile, 360-degree, free-rotation body. You build him yourself (easy-peasy if you’re over 10) and program him on your computer, tablet or smartphone. Comes out of the box pre-programmed with Assembly Checker and Program #1, so the fun starts right away. Use him as a light tracker or thermometer, or to play rock-paper-scissors or bowling, or as a notice board, calculator or compass, or as a pet who will follow you. He’ll do other things, too. Includes a 36-page manual, and all you add is a quartet of “AAA” batteries and some common hand tools.

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.

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+.

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.

Our robotic kingii dragon (Chlamydosaurus kingii, or frilled-neck lizard) is better than a puppy because you don't have clean up after it and it won't chew the furniture. This STEM education kit has (2) motors and digital control via IR sensors to activate LED eyes, motorized mouth and pop-out neck frill, plus "Escape" and "Chase" modes, which make it retreat and follow you using IR sensors, respectively. You'll need (4) "AAA" batteries and some patience, as this kit is delightfully challenging. Finished dragon will be 13-1/2" long x 8-1/4" x 5". For ages 10+.

The Tumbling Robot Experiment is relatively easy to assemble and has sensors in his (her?) belly, back and legs so he (it?) can fall and get up again, like some of us humans. At 8" tall, in between tumbles, it's a manic, sliding, chomping, swinging thingy, like a droid cookie monster in a Pilates class. You put a pair of "AA"s in his feet. 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+.

Takes a steady hand, a good eye and tweezers, along with wire cutters and needle-nose pliers, to construct these Metal Earth® steel models. Just punch out the tiny parts from laser-cut sheets and assemble them with tabs and slots—no glue, solder or screws required. You pick: the Apollo 11 Saturn V rocket and gantry, in stainless steel approx 5-7/8" x 2" x 1-5/16"; or the Kinkaku-Ji three-story Zen Buddhist temple in Kyoto, in gold-tone steel, approx 3-1/2" x 2-3/8" x 2-1/2". Full instructions included. For ages 14+.