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.

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+.

Make like a miniature Martin Scorsese and create your own (stop-action) movie. Best part? The actors are all Lego® people, who work for free. You’ll get (36) assorted Lego® pieces, including mix-and-match characters and props. Includes a 78-page guide with advice for making credits, sound effects, lighting, camera techniques, set design, backdrops, storyboards and a bunch more. If Hitchcock had had this kit, Janet Leigh might have survived the shower scene.

This little punch-out Triceratops puzzle can be a puzzle to assemble, with tiny pieces, but when done right will toddle along via the little wind-up gear motor. When done wrong, like we did, it will toddle in reverse, like a moon-walking dinosaur, which is even more fun. Measures approx 5" long when finished.

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.

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.

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.

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.

We spit on plastic. And so will you when you see these laser-cut bright steel models from Fascinations®. Snap-together pieces. The models are small, but worthy of permanent display, and designed for the grown-ups to assemble and display, rather than the kids to play with. You pick the Metal Marvels™ 3-1/2” long x 2-3/4” wide space shuttle Atlantis. (They aren’t making any more big shuttles, Pilgrim.) Or the 4-1/2” tall x 1-3/4” wide at the base MetalWorks™ Eiffel Tower.

For whiz kids, from ScienceWiz™. The Inventions kit has (4) projects: using a small motor as a generator; building a telegraph; a DC motor; and an AM radio. You add a D-cell battery and a few household items. Created by Berkeley science-education whiz Penny Norman, Ph.D., and attractively boxed, with a lavishly illustrated 40pp instruction book. For ages 8 to 80

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.

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+.

Knot everyone knows how much fun knots are. You can join the knot knowledgeable with Knots, Splices and Rope Work an 88-page soft-cover book originally published in 1917. Includes detailed instructions for tying many dozens of knots, ties, bends, hitches, loops, nooses, lashings, seizings, splices and things like the Matthew Walker, Selvagee Tie, Flemish Eye and the Topsail-Halyard Toggle. Includes (4) pieces of nylon rope for practice. Will tie up a kid for weeks.

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 kit has (2) motors and digital control via IR sensors to activate LED eyes, motorized mouth and pop-out frill, plus "escape" and "approach me" modes, which retreat and make nice, 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+. Check out our short video on Youtube!

You like spiders? This motorized arachnid model runs on salt water, which activates its magnesium fuel cell. Probably best if you don’t tell your mother. Finished model will be approx 4” long and wide, and will run for about 15 minutes per filling. You’ll get (3) replacement magnesium sheets, each of which will get you about 5-7 hours of spider operation (additional sheets available online). Includes a 20-page manual, and is designed for ages 8+.

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.

Impressive, this 3-foot Lizard King. The 1:14 scale plastic model of a Tyrannosaurus Rex skeleton has 51 bones that snap together, then snap apart easily for later use, which is more than you can say about the original. Measures 36" long, and comes with a display stand. Bones are nicely aged for paleontological verisimilitude. Very nice kit, with legs, as they say! For ages 8 and up.

This excellent and beautiful Stirling engine would make Robbie Stirling himself proud. Has a 1/2" piston stroke and sits on a 7" x 3-1/2" wooden base. Comes with a small alcohol lamp to fire it, and is connected via a belt to a DC generator that fires some blue LEDs. Includes a spare hot gas container, power cylinder and piston-sealing ring, needle roller and silicon tube, which you shouldn't need for some time. You also get a trio of Allen wrenches for your tweaking needs. This is the ultimate desk toy, or demo unit for the more serious-minded. Check out our short video on Youtube!