It doesn't get much cooler in the robotic-arm-kit game. The assembled STEM educational arm is 15" tall x 9" long x approx 3-1/2" wide. It's 2-pronged hand opens to 1-3/4", lifts up to 3.5 oz (100g), swings 120 degrees at the wrist, pivots 300 degrees at the elbow, and sits on a base that swings 180 degrees up and down and rotates 270 degrees, like, well, an arm. Controlled by (5) 2-axis joy-sticks and powered by (4) D-Cell batteries that you provide. Includes a hand-mounted search light and over-torque and gear-breakage alarms, which is more than your arm has. Requires a diagonal cutter and Philips screwdriver for assembly of its 200+ pieces and is made for ages 12 and up.

UGears® is the model company that specializes is wooden steampunk versions of otherwise simple objects, perfect for perfectionist painstakers who revel in constructing complicated kits. (You know who you are.) In this case, you pick: the (43) piece Steampunk Clock, a beautiful collection of gears, lacy ornament, flowers, stars and a moon that you make into an imitation clock approx 2" x 3" x 5" when done; or the Wheel Organizer, the world's most delightfully complicated desktop pencil and pen holder. The (51) parts include wheels, gears and slots that deliver the pencil of choice when you turn the big ship-like wheel. Finished model will be 4-1/3" x 3-1/2" x 3-2/3". No glue or special tools needed, and you can paint or stain them if you like.

Right after you build your own working medieval catapult or trebuchet. All you’ll need is glue, scissors and a steady hand (plus a small bag of marbles or rocks or something as a counterweight for the trebuchet) to construct these wooden, Canadian-made siege engine kits. The catapult stands 6” tall x 5” wide x 10” long and will toss assorted stuff 15 feet or farther, depending upon the stuff. The finished trebuchet will be 26” long x 18” wide x 24” tall and will propel small objects (meatballs?) 20 feet or more. Both include detailed instructions and are great resources for STEM activities. For ages 9+. Note: Please don’t propel small mammals, and please don’t put anyone’s eye out.

Make a whole bunch of fun and instructive Lego® machines/chain reaction models like marble runs and mousetraps involving ramps, buckets, funnels balances and much more. Comes with (33) Lego® elements, (6) Lego® balls, a dozen paper props, and a 78-page instruction booklet for (10) machines. You add a few common household items. Includes suggestions for more complicated devices if you have your own Lego® pieces, and if you don't, what are you waiting for? Ages 8+.

Start your children on the path to learning the basic concepts of solar tech. This multi-bot STEM education solar kit includes a 1.5V solar cell, a small DC motor and gearbox and a boatload of parts that will let you make (14) different comical and functional land and water solar-powered projects including: TortoiseBOT; SlinkerBOT; FourBOT; SurferBOT; PaddleBOT; WalkR-BOT; Big Wheeler BOT; CarBOT; TumblerBOT; BugBOT; K9BOT; MonsterBOT; CrabbyBOT and, you should pardon the pun, the RowingBOT. No, really--there's a row bot. Projects come in (2) levels of difficulty and include an 81pp graphic manual. You'll need a hobby knife or a pair of side-cutters, and sunlight. Most projects will be approx 5" tall when assembled.

From Elenco®, than whom nobody is cleverer, this MECH5 kit--a STEM kit--will make (5) robots, all of which use a mechanical coding wheel instead of software. They perform tasks, including forward, back 45 or 90 degrees, left or right turns, and modes to make bots draw circles, throw or push a ball, grip things, or act as a forklift. You add (2) “AAA” batteries for the small DC motor. Kit has (220+) pieces and the finished bots will be approx 6” tall. Ages 10+, but it’s intricate enough to need some adult help unless the kid is a genuine whiz-bang.

And this one will, running on rubber-band power after you spend a few happy hours putting it together. This all-wood, steampunky monowheel comprises (300) parts, and measures approx. 7-1/4" x 3-3/4" x 6-1/4" when completed. You'll see all the moving gears that run it in (2) modes: straight ahead with a turn-around finish; or continuous turning until it hits an obstacle, which means you can use it as a retro-futuristic bowling ball. Includes (19) spare parts.

Snap Circuits™ has added Brics, their name for little plastic building blocks that are, luckily, compatible with those other little, inerlocking plastic building blocks you have. This award-winning 200-piece Bric Structures set has sheets and blocks plus Snap Circuits connectors, blinking and steady LEDs, a slide switch, a fiber-optic bundle, an incandescent bulb and a melody integrated circuit, along with adapter blocks to mate the Snap Circuits components with the brics. Has instructions to make (26) electrified models, including a house and a tower, on the 10” x 5” base. You add a trio of “AA” batteries. For ages 8+. Winner of Six Toy of the Year Awards!

Sounds like a Europop group, but it’s actually your new tumbling pet. Also bristles his spines, rolls, spins and scurries. He’ll be a tad bigger than a baseball when assembled. The prewired circuitry is triggered by an audio sensor that will make him do multiple tricks when you applaud, and who else do you know who’ll do that? The solderless assembly, with over (170) parts, might be a tad challenging for the listed 7-10+ age, so we suggest some supervision. From Thames & Kosmos. You add (4) “AAA”s. (And he’s a hedgehog, so don’t expect him to share the hedge if you have one.)

The Junior Scientist™ series brings you the staggeringly clever wind beasts from Dutch artist Theo Jensen. These mini versions of his giant contraptions come with detailed instructions and history of the projects. Your Strandbeest (strand as in beach because it was made to walk on sand), will be about 8" x 6-5/8" x 4-1/4" after you assemble the 117-part wind-powered automaton. For ages 8 and up, the only tool you need is scissors.