We had this round Ikea mirror lying around our loft and I decided to make a nice frame for it without spending too much.
If you have everything ready, it shoult take you 1 morning to do it. It looks very nice and it has an "industrial look to it, Some indirect lighting will make a shadow that looks like a cogwheel. Try your own mirror shapes and staple orientation, I am planing on trying staples at different lengths to have a sun like frame look.

Step 1: You Will Need

This is what you need, more or less:

Mirror (any size... and shape I guess)
Piece of cardboard or wood. (Please reuse and recycle) has to be big enough to cover the mirror and at least have a 10 cm edge all around.
Glue (I used “Liquid Nails” adhesive at ~3bucks per tube)
Hot glue sticks and a gun.
1 pack of staples, I got a 25 000 pack from Staples for like 5 bucks.
Some cord or wire to hang it.
heavy duty scissors
x-acto knife or equivalent

A T-shirt if you are planning on taking pictures of your project. (sorry)

Step 2: Planning

Start by measuring your mirror, both diameter and perimeter.

If you want to know how many staples to use, 1 standard staple stick (average after they are interlocked) will give you 1.16 cm in length. Each box comes with 24 sticks (total of 5000 stapes) and each multipack has 5 boxes.
Each box will give you 28 cm

You can get a rough estimate with this formula:

(your mirror diameter * 3.14) /28= number of 5000 staple boxes you need.

for other shapes just measure the sides or perimeter and divide by 28.

Next, measure and cut your carboard (or wood). Draw a circle that measures 20 cm more in diameter compared to your mirror. I used a string and pencil to draw it. For this method you need to divide the diameter by 2 (i.e. the radius) and add 10 cm. this will give you enough room to put the staples. You can always cut any excess cardboard at the end.

Step 3: Fix the Mirror

Once you measure your cardboard you need to plan some sort of hanging device. I poked 4 holes, 2 on each side and passed a cord trough each side, I used a piece of plastic in between the holes so the cord wouldn't tear the cardboard over time.

Next thing to do is to attach the mirror to the carboard, I used a lot of hot glue and regular glue for this. I have no images but use what ever you have to make sure the mirror will stays in place. I which I had use wood or something more solid so I could use some 3M double sided mirror mount tape.

Step 4: Arrange the Staples

This is the fun part. The staples actually come interlocked in the box. so if you are careful, you can just take them out and spread them around the mirror 6 at a time.
Don't worry too much about alignment just yet, make sure you have the whole perimeter first.
Once you close the circle, try to align them evenly, you may end up with some extra sticks at the end. (as shown)

Step 5: Glue the Staples

You can probably use may different kinds of glue. Hot glue wound just make it. It doesnt come out fast enough, plus it dries to quick, if you want to make minor rearrangements you wont be able to with hot glue.
Get something that will dry overnight. The most important thing is that it comes with a long tip applicator that will fit under a staple stick.
Lay the mirror over a bucket or trash can, this way you can rotate it as you go.
Put the tip of the appicator as far as it can go underneath one staple stick and deliver the glue.
You will know is enough when you see the stick rise a little bit, then it comes back down.
skip the up side down stick and go to the next "tunnel". This will glue both upside down and right side up staples.
Once you go all around, leave it dry overnight.

This is your last chance to make minor adjustments to the staples.

Step 6: Hang It!

That's it.
Pick a good spot to hang it.

Use some indirect light to bring up the best shades and shines of your newly framed mirror.

Bonus mini instructable:

If you are wondering about my L shape shelf this is what it is:

We had 2 Ikea Lack shelf also laying around from our last move. I used one to showcase the mirror and couldnt find a use for the other. finally I placed sideways next to the other and everybody liked it!. so there you have it. I think a complete square would look kinda cool too.