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We love DIY projects here at Lifehacker. Whether we’re building computers, backyard projects, or turning office supplies into artillery, we’re always tinkering. Today we’re taking a peek at the most popular DIY projects of 2009.

Create Your Own Sun Jar: Lifehacker Edition

Inspired by a tutorial we posted last year, we decided to make our own DIY sun jars. The trendy summer time lighting accessory retails for $30+ but we were able to make ours for around $10 each. The sun jars proved to be our most popular non-computer DIY of the entire year and readers shared their own creations with us.

The First-Timer’s Guide to Building a Computer from Scratch

Building your own computer is a great way to get exactly what you want, the way you want it, without being constrained by the limits and high-prices of mass produced computers. We showed you how to build a computer from start to finish and have fun doing it.

Turn a Sharpie into a Liquid Fueled Rocket

What’s standing between you and some office mayhem? Certainly not a lack of Sharpie markers and keyboard dusting spray. Combine the two with this fun DIY project and you’ve got one of the most awesome pieces of office-machinery we’ve ever featured.

Properly Erase Your Physical Media

You need to be properly erasing your physical media: all the time, every time. Our guide will show you how to get the job done and done right whether you use software to scrub your disks or you send them to the great data mine in the sky with a 21-gun salute.

Turn an Old Laptop into a Wall-Mounted Computer

Why settle for a digital picture frame when, in the same wall space, you could mount an entirely functional computer/slideshow player/TV tuner? One Lifehacker reader turned an old laptop into a super-charged digital frame.

$8 DIY Aluminum Laptop Stand

We’ve always been keen on DIY laptop stands, but reader Aaron Kravitz—inspired by an attractive $50 stand—went above and beyond, creating one of the most attractive DIY laptop stands we’ve featured to date.

Build an IKEA NAS On the Cheap

If the Hive Five on best home server software got you excited about setting up a home server but you’re not keen on another unsightly PC in your home, check out this DIY IKEA NAS.

Build a DIY Portable Air Conditioner

We’ve shown you how to make an air conditioner (even for as low as $30), but what if you wanted something you can put in your car and take with you? While it’s no substitute for a fully-charged and factory-fresh AC system, it’ll keep you cool.

Turn a Bookshelf into a Secret Passage

Who hasn’t dreamed of having a mystery-story-style secret passageway? While a trick bookshelf is pretty awesome in itself, this secret passage hides a home office with clever style. One industrious Lifehacker reader and his girlfriend had grown tired of seeing their office from their living space, so they hid it behind a wall of books.

Wire Your House with Ethernet Cable

You’ve ripped a movie on your laptop, and now want it on that fancy new home theater PC next to your TV. If you’ve got the time, wiring your house with Cat-5e cable could make transfer times a distant memory.

Rain Gutters as Cable Management Tools

We’re all about creative cable management here at Lifehacker, so we were instantly drawn to reader Seandavid010‘s rain-gutter cable management setup. He was awesome enough to send detailed photos and step by step instructions to help other readers recreate his setup.

Build Your Own DTV Antenna

The lights went out on analog television this year and we were there with a guide to help you build a great DIY antenna for boosting your reception and getting that crisp digital picture you crave.

DIY Laptop Rack Hack Turns Your Monitor into an iMac

Lifehacker reader Matt Lumpkin saw our monitor stand from door stoppers post and thought we might like his laptop rack hack as another space-saving desktop solution for laptop-lovers. He was right.

Build Your Own Pizza Oven

Suppose you were inspired by the cheap DIY home pizza oven—but weren’t so sure your home insurance would cover oven modifications. It’s time to build a safer, more eye-pleasing oven, and we’ve got a thorough guide.

Crack a Master Combination Padlock Redux

Two years ago we highlighted how to crack a Master combination padlock for those of you who may have lost the combination to your bulletproof lock; now designer Mark Campos has turned the tried-and-true instructions into an easier-to-follow visual guide.

DIY Invisible Floating Bookshelves

We’ve covered the invisible floating bookshelf once or twice before, but if you liked the idea but weren’t keen on ruining a book in the process, weblog May December Home’s got you covered.

DIY Inverted Bookshelf

Instead of storing your books upright on top of the shelf, the inverted bookshelf holds all of your books in place using elastic webbing so you can hang them below the shelf—all the while allowing you to still take them out and put them back on as needed.

Build an Under-the-Cabinet Kitchen PC from an Old Laptop

Inspired by our guide to giving an old laptop new life with cheap or free projects, Lifehacker reader Brian turned his aging Dell laptop into an incredible under-the-cabinet kitchen PC.

Turn Storage Containers into Self Watering Tomato Planters

If you’d like to have delicious home-grown tomatoes but lack a garden to grow them in, you’ll definitely want to check out this ingenious and inexpensive self-watering system.

Deter Thieves by Uglifying Your Camera

A few years ago, blogger Jimmie Rodgers’s camera was stolen while volunteering in an impoverished Brazilian community, so he did what any sane person would do: He bought a new camera and made it ugly. With his uglified camera, Rodgers was able to snap pictures freely during the rest of his trip without worrying too much that his ostensibly crappy camera would end up stolen.

DIY TV or Monitor Stand from Door Stoppers

Nothing adds space to a desk or home theater setup like a simple monitor or TV stand, and weblog IKEA Hacker details how to build your own stand on-the-cheap with a few inexpensive items from IKEA.

Repurpose Your Analog Television

You don’t need to run out and buy a new TV because of the DTV switchover. If you did anyways, Make Magazine has put together quite a guide to giving old TVs new life.

Use Ping-Pong Balls to Create Diffused Party Lights

If you need some cheap and novel ambient lighting for your next party, you’re only a box of ping-pong balls and a string of lights away from solving your lighting worries.

Build a Custom-Made BoxeeBox

DeviceGuru blogger Rick Lehrbaum, inspired by the cheaper set-top boxes, made his own higher-powered “BoxeeBox” for the free, open-source media center. He posted all the parts, the how-to details, and lots of pictures.

Build a Sturdy Cardboard Laptop Stand

You already shelled out your hard earned cash for a swanky laptop, why drop more cash on an overpriced laptop stand? Cardboard alone can do the trick, as detailed in this step-by-step tutorial.

Install Snow Leopard on Your Hackintosh PC, No Hacking Required

Earlier this year we put together a wildly popular guide to building a Hackintosh with Snow Leopard, start to finish, and then followed it up with an even easier guide to install Snow Leopard on your Hackintosh PC, no hacking required. Computers + DIY is all sorts of geeky fun waiting to happen.

Have a favorite DIY from 2009 that wasn’t highlighted here? Sound off in the comments with a link to your favorite project. Want to see more popular DIY guides courtesy of the ghost of Lifehacker past? Check out our huge DIY guide roundup from 2008.