This is an idea I got from Pinterest. But modified for my use. I hope you like it.

Oh yeah the fabric helps to give some friction so magnets don't seem to slip like they do on smooth metal.

Here is a commercial type board that is smaller, less attractive and cost more.

http://www.globalindustrial.com/p/office-school-supply/boards/bulletin-boards/magnetic-fabric-bulletin-board-3-x-2-aluminum-frame?infoParam.campaignId=T9A&gclid=CNPh1-DLiroCFdSd4AodOSQAXQ

Step 1: Materials and Tools

MATERIALS:

Piece of Metal. (I used an Oil Drip pan from Wall-mart @ $12)
Spray adhesive or contact cement. (I used + Loctite spray Adhesive)
Fabric of your choice (I used fabric remnants I had.)
Screws for hanging

TOOLS: Needed for making holes in metal!

Center punch
Hammer
Tape measure
Drill
1/4" drill bit
razor knife or scissors

Step 2: Putting in the Hanging Holes and Prepping for Adhesive.

1. Decide where you want to put your hanging holes. I put mine 4" in form each corner a total of 4 holes.
2. Mark out all holes to be made.
3. Use your center punch to start holes and pin point exact location for drill bit.
4. Drill holes with 1/4" drill bit. (I used a wood backing block to reduce blow out)
5. Tamp area down against backing block using a hammer to reduce burrs.
6. Decide which side of the metal to use. (I used the back of my drip pan because I wanted the added depth off the wall)
7. Clean up the side you decide to use. Remove any stickers, glue, grease, dirt, ect

Step 3: Decide How to Lay Out Your Fabric.

My wife wanted me to use some fabric we had that she liked. Unfortunately it was too short, so I had to improvise and use two materials. I first laid out my main fabric then I chose the second fabric and laid it.

Don't forget to test your fabric magnet board with some magnets. Just in case you chose to thick of a fabric.

Step 4: Glue Time!

Read all the instructions on your glue including the safety and precautions.

I applied my glue outside away from anything that could get damaged from it.

1. Roll up fabric after you have decided on your lay out. This way once the glue is ready you can just unroll it back on. (if you have two fabrics you will do the first one, then do the second one.
2. Spray glue on to the side you want to use of the metal surface. (Don't worry about the sides or back yet. Just focus on the top part.)
3. Let glue set for 1 or 2 minutes to get tacky. (this is according to my glue, if you chose another type then read the directions)
4. Unroll fabric on to metal the same way you rolled it off the metal. Don't worry too much about it not being perfect you have plenty of time to work with it and stretch it out.
5. Now start at you best starting point. (Mine was a line in the fabric. I decided you put the line on the bend in the metal. It just laid out perfect like that. So I focused on getting that line straight.) Get your starting point straight and anchored well.
6. Now work from your starting point out. You will have to lift the fabric and stretch it. Don't lift it to far or you may release your anchor point. If that happens it fine just go back and re anchor it. (Wrinkle free fabric works best but you can stretch out wrinkles it just takes more work. Work all the way to the other side.

Don't worry about the over hang just yet.

Here is a video of me glueing the edges. http://youtu.be/xPzIcxBbt9I

Step 5: This Step Is for a Second Fabric ONLY!

I you are just using one fabric just skip this step and go to the next one.

1. Decide where your second fabric will be laid out. You also need to take in consideration the seam where they meet. I used a finnished edge, you could also use ribbon, rope, twine, or just hem the fabric with a sewing machine. (You can over lap the fabrics, but once again check to make sure a magnet is strong enough to attach and carry weight.)
2. Mark a light pencil line on fabric to give you a guide line. For reinstalling the second piece of fabric.
3. Lay down card board or mask out the area you are not putting the second piece of fabric. Masking out the area works better, I used card board so a little over spray got where I didn't need it.
4. Spray adhesive on the new area. (You can spray it on the 1st fabric if you are overlapping.)
5. Do the same as before. (I started on my seam line, then worked back off of that.)

Step 6: Finish Off the Edges.

1. Now cut the remaining fabric away leaving about 3/4" or so.
2. Flip the your project over now. (Make sure your work surface is clean)
3. Spray the perimeter of the back of the board and fabric with glue.
4. Wait 2 minutes.
5. Using your thumb and index finger, go around the edges slowly working the material up. (I made about 5 passes or more around the board, Slowly pushing the fabric into place. Always work toward your corners first, then finish out the corners.
6. The fabric should wrap the sides and a little of the back.
7. I used my drill and drill bit to open up the fabric that covered the holes. Be careful not to damage your fabric. You could use a knife or punch.