For my new (and very small) bathroom, I wanted to make some shelves. I'm not really sure how definite the shelves will be. So I didn't want to drill any holes in my new tiles. Besides that, the tiler told me that my tiles are extremely hard and therefore almost impossible to drill into.

I never like to glue shelves, because glue will get old and the shelves might come down in time.

My bathroom is small, but big enough for me. The small size of my bathroom is an advantage when I want to clamp my shelves in place, so that is what I did.

You do need two walls close to each other to clamp the shelf in-between.

Step 1: You Will Need

Materials

Shelves:

wood
wood-glue
laquer

Clamp:

aluminium or inox 15 x 15 mm L-profile
aluminium or inox 15 x 15 x 15 mm U-profile
Inox screws
Inox nuts and bolts (M6)
rubber blanket
contact cement

Tools

Shelves:

wood clamps
brushes
saw
router

Clamp:

drill
screwdriver
10 mm spanner (2x)

Step 2: The Shelves

I will not really go into detail in how to make the shelves. You can make them however you please.

A few things are important:

The length of the shelf needs to be just 2 mm shorter than the space between the two walls.
The shelf needs to be strong enough to hold the power of the clamp. Both the pushing strength and the screws that hold the clamp.
To hide the clamp it is nice to have a lip in front of the clamp.

Step 3: Prepare the Metal for the Clamp

To make the clamp you will need some metal profiles that doesn't rust. In a bathroom, that would be a problem.

Measure the width of the shelf behind the the lip.
Cut two pieces of L-profile and one of the U-profile to the width of the shelf.
Drill four holes in one side of the L-profile. Big enough for the inox screws to fit through.
Do the same with the other L-profile.
Clamp or hold one L-profile to the U-profile.
Drill two 6 mm holes through both the L-profile and the U-profile for the M6 bolts to go through.

Step 4: Add the Rubber Blanket

To really give the clamp some holding power, we need to add some rubber. I used rubber from a rubber blanket that offset printers use and throw away every now and then. You can also use rubber from a inner tire or something you have.

Measure the size of the cut profile.
Cut the rubber to size. (2x)
Glue the rubber to one L-profile. (on the outside of the side where not the holes are)
Glue the other piece of rubber to the U-profile. (on the outside of the side opposed to the side with the holes)

Step 5: Test Fit

This is a good moment to test fit het clamp and pre-drill all the holes.

Put the L-profile with the rubber on it on one edge of the shelf, with the rubber just outside the shelf.
Hold it firmly in place.
Mark the four holes with a drill that is just smaller than the screws.
Remove the L-profile.
Drill the holes. Make sure that you don't go through the other end.
Screw the L-profile in place.

Put the bolts through the 6 mm holes of the L-profile from the inside out.
Put nuts on the bolts. (just 10 mm in)
Put the U-profile on the bolts.

Place the two profiles with the bolts on the other side of the shelf with the rubber just inside the shelf.
Mark the holes for the screws with the small drill.
Remove the profiles.
Drill the holes for the screws.
Screw the profile to the shelf.