Several months ago I got this nice photophore you can see above. It has a solar panel on the top so it can charge its batteries during the day, and at night there is a LED that lights up. It is really nice!

But I was quite embarrassed because I had no idea where I could place it. I live in a relatively small apartment so I do not have a lot of furniture, and it is full of basic stuff already (3D printer, PLA spools, soldering iron, Arduino boards, jumper wires...).

So I thought about a shelf that would fit into my apartment to hold this photophore. Small, close to the sunlight, removable. Impossible? Well, actually I have made a perfect mini floating shelf!

What you will need:

2 suctions cups.
A rope (about 1 meter should be large enough).
A 3D printer / or a service to 3D print the pieces. Or you can also try with wood.

Before to start:

Is it solid enough? It depends on the suction cups you use. As described in the next step, I have used homemade suction cups to increase their strength. And now it has been almost a year that this floating shelf is standing on my window with the photophore (made out of glass), at a height of 1m50. So yes it is solid enough if you are careful and use suitable materials.

STL files: if you want to print these pieces, you can find the STL files on my Thingiverse account here, or in the next step of this instructable.

Step 1: Materials

This mini floating shelf is based on 3 main part:

The suction cups to hook the shelf to a flat and smooth surface.
The plate to place the objects.
The rope to attach the plate to the suction cups.

The suction cups:

The most important elements are the suctions cups. A few months ago I made lever suction cups to increase the strength of the suction cups, and it worked quite well. Here is a link to the instructable.

Basically, a lever suction cup is made of 5 elements:

The suction cup of course. You can find some in any supermarket, probably in the bathroom section.
A "base" which presses the edges of the suction cup onto the window. Here I have called it the "cup".
A grabbing piece. The lower part grabs the top of the suction cup (that is why I called it the "grabbing piece"), while the upper part (a cylinder) passes through the "base". And it has a hole at the top to fix it to the lever.
The lever. Actioning this lever helps to decrease the pressure inside the suction cups, which make it stick better to the surface.
Then a kind of nail to attach the "grabbing piece" to the lever.

Of course, you can also buy your own lever suction cups, or use some regular suction cups if you think they are strong enough.

The plate:

I have 3D printed a plate, but this can be done with wood or any other material (recycling a plastic bottle ?). It is a square with edges of 11.5 cm (just enough to be printed with my MP Select Mini!). There is also a border, in case the object placed on the plate slides. And finally, there are 4 holes in these borders to attach the plate to the suction cups with the rope.

The rope:

Finally, I have used a rope. It is a bit rough, so it does not move too much and the plate does not slide (as explained in the next step).

Step 2:

To attach the rope, I have used 2 different methods:

First method: I have used 4 pieces of rope. Each piece connects a corner of the plate to a suction cup. This technique has the advantage of being very stable, the rope cannot move. But on the other side, it is more difficult to make all the 4 knots at a good distance so the plate is perfectly horizontal. Below is a scheme of the shelf seen from the side.

Second method: I have also used only 2 pieces of rope and I have made a loop on the suction cups. Each piece is connected to a single suction cup. With this technique, it is possible to adjust the length of the rope on each side. But the rope can slip and the object placed on the plate can fall. So this has to be done with a rough rope. I have used this technique lately, and it works perfectly.