*1 piece of wood (eg. oak) of ~ 80 * 3.5 * 1 cm (32" * 1.5" * 3/8")
* 64 wine-corks
* wood-glue (preferable waterproof)
* wood oil
* Saw, preferable a jig saw
* Cutter knife
Time : takes about a day to complete : mainly because you need to glue a row of corks, and then wait for the glue to dry.
Step 1: Make a mold
It is very simple : cut a square hole out of a piece of leftover wood, eg an MDF board. If you want to make a lot of pot holders, you can cut several mold-holes out of the same board.
Step 2: Cut outsides - assemble frame
After experimenting, I've found out that the inside needs to measure 170 mm (6.7"). I guess that corks are about the same size all over the world, but to be absolutely sure I recommend that you double-check this : squeeze 8 corks in a row, and measure the lenght.
If you want to make smaller (eg 6*6 corks) or larger (eg 10*10 corks) pot holders, you need to adjust the numbers based upon this measurement.
In fact I think that a set of 3 pot holders, 6*6, 8*8 and 10*10 would make a very nice set :-)
If you have experience with cutting wood, you could make a miter joint, which will look more professional.
Then apply glue to the 4 pieces, place them into the mold : this will ensure that the frame is flat and square. Let it dry a couple of hours
Step 3: Adding the corks
Take 8 corks and trim their length with the cutter knife if they would be longer then the frame's height. Warning : cutting a cork is not that easy, and so you need to be careful. I found that this works best : cut the cork as deep as you can, then roll the cork so it rotates about 45 degrees and cut again, repeat this until it is cut completely.
Then put the 8 corks into the frame : keep the cut side up (so they all align with their top side at the bottom)
In case there is too much pressure to fit the corks, you can slice off a bit of one or more corks that seem to be too big..
Then apply glue to corks : glue to where they touch the frame, and glue to where they touch each other.
Use a leftover pice of wood to temporary keep the corks in place. Check the pressure, alignment. Let it dry
Remark : some glue may/will drip through, so be carefull about the surface you are assembling this on...
Wood glue can easily be removed with water as long as it has not dried completely.
Step 4: Finishing
Remove exces of glue by cutting it away with the cutter knife
Sandpaper the outside frame until it is smooth.
Apply wood oil and let it dry. I often use wood oil from IKEA, which is good, cheap and doesn't smell.