The MakerBot designer says kids get it right away, and that’s probably because early users are mainly making toys with this thing. Go to thingiverse.com to see 15,000 project plans, such as knights and princesses, rocket ship inhabitants, neckties and so on. (Actually, Bob has a home-printed silk tie made 15 years ago with a Canon inkjet printer.)

Another hand in this game is 3D Systems, which makes “The Cube.”  They invented this kind of 3D printing 25 years ago. They make industrial strength units for sculpting prototypes from drawings, and they sell the units for tens of thousands of dollars. This is a much more sophisticated kind of model making machine and they say they will produce a home version for around $1,300 some time later this year. See some of their solid-printing results at Cubify.com. Design models can be quite intricate, but are limited to 5.5-inches in any direction.

Nano Watch

– Motorola has a new smart watch with enough features to keep a fitness buff humming. The “MotoACTV” is a GPS plus music player wrist watch that figures out which songs make you exercise harder and plays those more often. It does its figuring by monitoring your heart rate. It  tells you how many calories you burned and your average workout pace. It uses Bluetooth to talk to you through a headset. It can also broadcast FM radio. It’s $250 for the 8 gigabyte version.

– You can turn an Apple “Nano” music player into a wristwatch just by adding a strap. We saw some at Amazon for $23. They even had leather ones. If you use a leather strap and fix the Nano face to show the time, it looks like a regular wrist watch. To keep the clock face on top, go into the Nano’s settings, choose the clock app and choose the setting that puts the clock up front when the Nano wakes up from its sleep mode. Voila, it’s a wristwatch.  We just ordered one. See also the TikTok watchband at the Apple store.

– Another way to go is the “Striiv” pedometer, $99 from Striiv.com. Anyone who thought a pedometer was just for counting steps hasn’t seen this thing.  It has games to encourage you to walk past the 4900-step American daily average. You also earn points you can spend creating a virtual enchanted island on their web site. The more you walk, the more money the company donates to saving trees in the rain forest or polio vaccines.

The email messages coming in on the watch, however, are read-only. Answer them with your smart phone.The “I’m Watch” sells for $350 from an Italian company of the same name.

– Sony’s “SmartWatch,” appears to be a similar device, scheduled to come out in March; pricing not yet determined. It will communicate with an Android smartphone through the Bluetooth short range wireless system. It too lets you take calls, see email, or play music and games. Don’t dunk it in water, but it’s OK if it gets a little wet. The display is 1.3 inches and like the “I’m Watch,” it looks bulky on slender wrists.

You install the tiny camera using your license plate bolts, and use the Magellan Roadmate 9055 GPS device as your screen. At seven inches, it’s a smaller screen than the ones that come in many new cars but larger than most GPS screens. The Roadmate gets great reviews because of its favorites menu, lifetime traffic alerts, points of interest info and member assistance from Automobile Club (AAA).

We saw the camera advertised for $150 and the Roadmate GPS viewer for $257 at Amazon. That makes it a bit over $400 plus some handyman skills to set this up. Some wiring to the taillights is involved because you want the camera to start broadcasting what it sees as soon as you put the car in reverse.

We tried out a “Stylus + Pen + Laser Pointer” from Griffin Technology and it worked very well. The soft rubber tip gives you nice control when you’re tapping, dragging or sketching on an iPad or iPhone.  It’s $50 from GriffinTechnology.com.  Also check out the $16 styluses at Targus.com.

• Contacts Plus is a $2 app that brings in birthday information from Facebook and other sites. It also lets you send files from your tablet to your computer, phone or other devices. Google “Barnes and Noble Contact Plus” for more info.
• The Facebook app (free) is a handy way to keep up to date on Facebook. “Friendcaster” does this as well and adds a few more features.
• Evernote has been around for many years and is a nice free note-taking app.

About 90 percent of all wheelchairs are push-rim propelled. With the RoChair, one push-pull of the adjustable lever arm rotates the chair’s front wheels up to two revolutions, depending on the gear you choose. Hills are no problem, they say. (We guess it depends on the hill.) We hope the price comes down, because it’s $5,000. More info at rotamobility.com.

Road Mice from Four Door Media also come as Lamborghinis, Mercedes, Fords and others, The price range is $35 to $50. They’re compatible with PCs and Macs.

• IBM is working on computers and phones that respond to your thoughts. Think about calling someone and it happens.
• Also on that track are a number of companies promoting TVs that let you change the channel just by thinking about it.
• The “LightPad” is a device that connects to your smartphone and projects its display onto a 60-inch screen. It includes its own keyboard and an eleven inch rear-projection screen.
• “SunBrite TV” lets you watch your favorite shows in bright sunlight – like out in the yard or on your boat.
• The Novo 7 is a $99 Android tablet complete with the latest “Ice Cream Sandwich” operating system. It’s the cheapest we’ve heard about, if you don’t count the $100 LeapPad for children, which sold out this Christmas.

We have both tablets, so it’s easy to compare them. Joy finds she likes the small size and light weight of the Kindle Fire, just seven inches and 15 ounces. That’s nine ounces heavier than a regular Kindle, but seven ounces lighter than an iPad. The Fire is easy to throw into a purse or a bag. And it’s easy to hold in your hands for long stretches. In fact you can easily hold it in one hand, which is quickly tiring with the iPad.

The Fire’s “carousel” main page shows dozens of revolving images, representing your apps, books, videos and magazines. It’s very easy to navigate. You can use your finger to pin favorites to a shelf below the main screen image or move to other categories by tapping a link at the top of the screen. The links point to music, videos, apps, Web sites, documents, etc. If you’re already using Amazon’s Cloud Player for music, or getting free movies through a subscription to Amazon Prime, the Fire handles all that plus Netflix and games like “Angry Birds.”  We like it that you don’t have to type in a password every time you add an app.

The Fire connects to the Internet through a WiFi connection. Apple has a WiFi-only version of the iPad and another that adds a 3G cellular phone connection. You pay more for the cellular version upfront, plus a monthly fee. You may not mind the absence of 3G on the Fire, since much of your reading takes place offline. You save money by not having monthly charges.

Our favorite free news app is “Pulse.” This comes with stories from the Wall Street Journal, ESPN, and a dozen or so magazines and blogs. Turn on the Fire for a few seconds before you leave the house and those stories will quickly download. They will then be there when you’re offline on the bus or at the dentist’s office.

When the iPad first launched, a dozen how-to books immediately followed. We haven’t seen any yet for the Fire, which is an indicator of how easy it is to use. But of course there are books on how to use the iPad because it has more functions.

The bottom line: If you plan to use a tablet for business or creative tasks, get the iPad. If you like a larger screen, especially good for magazines, which tend to spill off the page if you enlarge them on the Fire, get the iPad. If you need a 10 to 12 hour battery life, get an iPad. In fact, the iPad is a charmer. Play around with one at an Apple store and see if you can get out the door without buying it. We couldn’t. But if we hadn’t already bought the iPad, the Fire would easily be enough for us – and the $300 savings is appealing.