Under the kitchen sink is an excellent place to store a great many things. It's handy, it's centralised, and it probably already has a child-proof latch. As a result, there is almost always more stuff to keep there than there is actually space to keep it in. If nothing else, things get lost behind the pipes and hoses, and the little containers get hidden down between the bigger ones.
At the same time, it's important to avoid blocking the water supply- if anything ever goes wrong with the sink or the dishwasher, you have to be able to get in there and shut it off. This shelf slots into place, so that you can pull it out at a moment's notice.
The shelf that I built fits into the corner, taking advantage of the otherwise dead space beside the disposal. It rests on brackets on one side, and slots between upper and lower brackets in the back. It can hold a surprising amount of weight. The dishwasher hose loops around it, and it doesn't block the shutoffs. If anything ever needs to be shut off, disconnected, or re-connected in a hurry, all you have to do is pull the shelf straight out.
Step 1: Tools and Materials
Tools you will need:
1. A drill and bits
2. A screwdriver
3. A pencil
4. A level that is small enough to fit in under your sink
5. A tape measure
6. A straight-edge
7. Saw to cut the board to size (not shown, since the board I had was coincidentally a good size already)
Materials you will need:
A. A board to make the shelf out of
B. Angle brackets (6)
C. #6 screws (8)
Because you will be working in an area that has lots of water and electrical hook-ups and you can't be quite sure where they run, I recommend setting the bit on your drill quite short, and plugging it into a GFCI outlet if at all possible.
Step 2: Measuring
First, figure out what you have to work around. In this case, it was the dishwasher drain, the garbage disposal, the disposal power, the water supply, and the wastewater pipes. Use the straightedge to nudge any flexible hoses aside and visualise how a rectangular shelf would fit into this space. Work out how wide the shelf can possibly be without kinking the hoses. Then, work out how long the shelf can be, and still allow the door to close.
In my case, I had a re-used particleboard shelf that was a nice width already. All I had to do was figure out how long to make it. There was already a paper towel holder in the cabinet, so I cut the shelf short enough to leave an inch clearance between it and a full roll of paper towels.
Step 3: Making Guidelines
Use the straightedge and level to draw guidelines long and wide as your board. Then, measure the thickness of the board, and draw a set of guidelines above where the board will sit. Making sure the bit on your drill is set short, drill the starter holes for the brackets on the guidelines.
As it turned out, I had to re-do this step. The floors in my house are nothing like level, so the little shelf, level with the floor, turned out to be much too tilted to use. That was where the spirit level came into it- I re-did the lines and starter holes based on actual horizontality, rather than my home's bizarre opinion. Happily, it's under the sink; no-one will notice. I suggest that you make the shelf truly level as well- since it's only bounded on one side, things will roll off easily if it's crooked.
Step 4: Install the Brackets and Shelf
Once you've got your starter holes, you're almost done. Screw the bottom brackets, side and back, in place quite firmly. Set the top ones, back only, in place loosely. Slide the shelf onto the side brackets, and push it in between the upper and lower brackets in the back. Press the upper back brackets down onto the shelf, and tighten them in place. They act as a clamp, supporting the weight of whatever you put on the shelf.
I'm sorry I don't have a good picture of the final step; the presence of the shelf pretty much hides the brackets.
Step 5: The Finished Product!
All of your small items are off the floor of the cabinet!
Step 6: While You're at It
While you've already got the drill out and the bit set short, you can install some hooks on the insides of the cabinet doors to give yourself more storage space. Make sure that neither the drill bit nor the screw end of the hook is long enough to poke through the cabinet door.