So I'm a 3D designer, and I have a 3D printer. I also think I have carpentry skills. So I wanted to make a special shelf. One that used my 3D designing and printing skills and minimal carpentry skills.
So, what you'll need:
1) Access to a 3D printer. But you could make the anchors without a printer.
2) A drill and 2 screws
3) A board of desired dimensions. I found mine in my attic, it's a 1" x 6" (3/4" x 5-1/2") that's about 24" long.
4) Some string. I had a ball of twine that I used.
Step 1: Prestep 1: I Made a Prototype
So first I made a prototype. I wanted a shelf that looked like a suspension bridge. My first idea was to have at least one wall anchor (one worked in holding the shelf so I didn't have to print another), and only 2 shelf anchors. I realized this would leave the shelf unsupported in the back, so I printed a little L shelf to hold the back. Basically it looked cool but wasn't very great. But worked as a proof of concept.
Step 2: Real Step 1: the Plan
So I went with really suspension bridge looking. A wall anchor on each side, and 7 anchors on the shelf. You only need 2 shelf anchors, one against the wall, and one at the end of the shelf. But like I said, suspension bridge looking. So I printed out the wall anchors, that have a cylinder to hold the string and a hole to mount on the screw. Would work just as good to tie the string to a screw in the wall, or use a hook. And I printed the shelf anchor, which is just a cap on the end of the board with 7 cylinders to hold the strings. These are only held by friction and other angular forces. Again, you can use whatever as anchors, as long as you have one close to the wall, and one at the edge of the shelf. Mine is not fastened to the shelf, so it goes under the shelf about a half inch and has a cap at the end to keep it from sliding towards the wall. I wanted mine to be be 12" tall, because I'm american, and 12" is a foot. I made my anchors 1" apart. From here, I used complex math to determine the lengths of string needed for each anchor. I went to this site (http://www.cleavebooks.co.uk/scol/calrtri.htm) and typed in 12 as the length of one side, 1-6 as the length of the second side, and hit calculate. It will give you the lengths needed and even the angles (notice my anchors are angled). Then I used more complicated math to determine how much extra string I needed for tying the strings to the anchors (I guesstimated an extra inch).
Step 3: Step 2: Assembly
If you have more strings, assembly is more fun! As in, you have to prevent your strings from getting tangled as you assemble! I tied a very simple slip knot with the string, leaving as little extra string as possible, then pulling it tight. I uploaded a how to tie a slip knot image. The way that worked for me was to tie all the shelf anchors first, then tie them to the wall anchor. I also tied them to the wall anchor in order by length because OCD and I figured it would look better. Don't know if it effects the look or knot (spelled wrong intentionally).
Step 4: Mounting
Find a spot that you can hang your shelf. Find how high you want the shelf. Add the height that you made for your shelf. Screw in 2 screws at a distance equal to the length of your board (I also subtracted the distance of my anchors from the edge cause OCD). I put my screw in with about 2mm left out to slide my anchors on. Attach your anchors, attach your shelf, and tada! Put stuff on it to make it look pretty. I've attached my anchor files, if you want to use them. If you want new files or different files, or printed parts, or need a 3D model or print of something else entirely, you can contact me and we can work something out.