Shelving. We all need it, but it is expensive and not terribly sturdy. For a fraction of the cost, you can assemble your own shelves using cut-to-order pieces of wood from Lowe’s or Home Depot. The trick is to plan ahead so there is minimal waste product afterwards. Generally building shelving to fit a space generates more waste than using wood optimized for the lengths that the wood is offered for sale. Also, adding a backstop for each shelf, while relatively simple, requires tools and extra lumber. I will walk you through the simplest design to give you an idea of what you need.
Tools. Bare minimum, to make a quality product, you will need a power sander (I use the Black & Decker Mouse sander, very inexpensive), a power drill/driver (an electric screwdriver is really not enough to do the job properly), a small drill bit for pre-drilling holes, and either clamps or an extra pair of hands. Hardware requirements are limited to 2″ coarse thread drywall screws and L-brackets (1/2 by 3/4 inch) for extra strength if you need heavy-duty shelves.
Workspace. I do all my work on the garage floor or across a pair of cardboard boxes I use as a workbench. Once you have sanded it is a good idea to have cardboard under your work to avoid deep scratches from floor debris. The rough sanding I do before anything else, to give a reasonably smooth finish, prevent splinters, and possibly not have to sand it again.
Purchasing the wood. Wood usable for shelving generally comes in 6″ to 12″ widths, 1″ thickness, and 4′, 8′, and 12′ lengths. Always check for warped wood before you take the wood to be cut. Once cut, you own it. To get 4 shelves roughly 3′ wide, simply ask to have a 12′ length cut into 35-3/4″ pieces (this avoids tedious math and extra cuts at home due to the thickness of the saw blade). For the sides, if you want about 11″ high spaces just take 4′ pieces the same depth as the shelf pieces and at home mark off every 11-3/4″ from the top down. This will allow a small gap at the bottom so the sides also serve as feet. Make sure all measurements are taken from the top edge and not from any other marks you have made to avoid compounding tiny errors in measurement.
Plans. ALWAYS diagram your design on a scratch piece of paper and calculate how many board feet you need before going to the store. Also determine which lengths best suit your needs so you can load up the cart one time before heading to the saw station. In the above example I would need one 12′ board and 2 4′ boards (not one 8′ board cut in half)
Once you get home and have sanded all surfaces besides the end grain, look at the patterns formed by the wood grain and lay out your pieces in their desired positions cosmetically. Start by pre-drilling holes through the sides into the end of the top shelf, two on each side, using a drill that is the size of the screw without threads. This will prevent the shelves from splitting as the screws take up space inside the wood. Methods of aligning the pieces for this process are varied. I use clamps and a 3″ x 3″ block to form the corners. This is where you can absorb and correct small warps. Make all the holes accurately and when you drive in the screws it will force the shelf into alignment. Once the top shelf is attached, install 4 L-brackets if you are using them on the underside of the shelf.
Repeat this process for each shelf and you will be done before you know it. I have included some photos of finished work to give you some ideas for bookshelves, DVD racks, and speaker stands. Fell free to ask any questions in the comments, just remember I am not a professional carpenter. I just needed some furniture and had a really tight budget.