For anyone who wonders how well projects stand up over time, this first photo was taken about three years after these shelves were installed. We needed a place for the towels, so my wife envisioned floating shelves. She suggested making them from a door, which she had seen online. The rest is history...

Step 1: Tools and Materials

Tools

Table Saw
Chisel
Drill
Socket wrench

Materials

Hollow interior door - I picked up mine from our local Habitat for Humanity ReStore for $29.
2x2 inch wood (2 feet plus the width of each shelf) x (number of shelves) - scrap or leftover 2x4 studs are a convenient source
Lag screws
Deck screws
Wood glue

Step 2: Cut Out Shelves From the Door Corners.

Once you decide how big to make your shelves, cut that size from the corners of the door with the table saw. If you choose the right sizes, you can use the whole bottom and top of the door, or a whole side. My shelves are 25 inches (64 cm) wide and 12 inches (30 cm) deep. Reach inside and pull out the support material between the panels. You can scrape off what's left with a chisel.

If when you cut out the size you need, two edges are hollow and two are solid, you need the other short edge to be solid, so cut a piece of your wood to fit and glue it in. Now you're ready to cover the edges.

Step 3: Cover the Edges

Let me start by saying that if you just want to paint the shelves, all you need to do is sand up to 220 grit, seal or prime, sand lightly with 220 grit, and paint.
If you're a glutton for punishment like me, you can inlay pieces of the door's veneer on the edges. Here's how I did that:

Cut out more pieces of the door to the dimensions of the three solid edges of your shelves. For example, mine were two edges of 1-3/8x12 inches and one edge of 1-3/8x25 inches. While the support material (cardboard) is still in these pieces, you can set the table saw at 45º and cut all around, as shown in the first two photos. Then you can clean off the support material away from the panels with a chisel (photo #3). You can cut the shelf all around with the table saw at 45º, a bit deeper than the thickness of the door panel.

Then with a dado stack or square shaper as shown in photo 4, you can cut a recess the depth of the panel thickness so your bevel-edged panel pieces fit in nicely as in photo #5.

After all this fun, I stained it dark dark dark with an ebony stain, then applied a few coats of polyurethane.

Step 4: Make the Bracket

Whew!

This is another easy part. Make a "C" shape as shown from your wood to fit inside the hollow shelf and screw the pieces together. Mine happen to be two pieces 1-1/2 x 1-3/16 x 10-1/8 inches and one 1-1/2 x 1-3/16 x 22 inches.

Step 5: Mount the Bracket

Find the stud(s) behind where you're mounting the shelves and mark the bracket for a hole just bigger than your lag screw(s). Mount to the wall as shown. If you only have one stud behind your bracket, you can also add some wall anchors and screws like I did. The lag screw will hold the weight, but the anchors will keep the shelf from tipping to the side.

Step 6: Mount the Shelves

This is the easiest part yet. Slide the shelves on over the brackets. Done!

Step 7: P.S.

If you like this style of step-by-step instruction, please share with others and subscribe, so you'll be notified when I post more. If you have questions, please post them in the comments. I will try to answer and probably update the instructions, too. Read about more of my woodworking projects and tools at ChipsWoodShop.com.