First, remember that it is not a permanent mold. It could be used a couple
of times and maybe more.

You need a 4 " thick styrofoam block which is about 5 inches wider and
higher than your original gear. Put the styrofoam block flat on the table,
with the gear on his side in the middle, and trace with a felt pen the
outside and inside of gear on foam. Remove the gear and on a bandsaw, cut
off the center part between the lines, which is the thickness of the gear.
Cut the bottom part of gear( where axle bolt)  1 " longer than original for
trimming.You will keep top and botton foam parts.Then you will use
lithoplate thin aluminium, 4 inches wide and you will glue it on the inside
of the top and bottom foam mold. You can use latex contact cement. This will
make sure that epoxy curing wont melt foam and make it easy to remove.After,
trace on aluminium with permanent felt pen, the pattern of the gear at max
width, here 1.5". It will help to lay strips straight on mold.

After that, you will need carbon fiber cloth ( 5 or 6 oz), a few pieces of
kevlar, and 8 or 10 ounces fiberglass cloth. You now have to determine the
thickness of your gear. For my plane, i made it about 3/8 " thick. You also
determine the maximum width of your gear. Mine is 1.5" on bolting side,
going taper to 1" down at the axle  spot.

After this, you will cut your material. It is better to cut all cloth at 45
degrees of the weave. I use about 80 % of CF, 15% of FG cloth and 5% of
kevlar. I cut  my material according to the max width of my gear, in that
case 1.5". You will trim to taper shape on bandsaw after curing.

Then, you will put PVA or mold release wax wax on both aluminium lining.
Then, after mixing your epoxy, you start laying one strip on bottom part of
mold which is sitting on a piece of waxed paper on your table. You wet iot
with a brush, making sure you remove air bubbles. After you put another
strip  and do the same. Alternatively, you also lay 5 inches long kevlar
cloth in the 4 radius parts of gear. It will help for stretch strenght. You
can put 2 layers on each radius , after the 3 rd  layer of CF and 3rd.
before the last. You will put about 4 layers of FG cloth in the middle of
the CF layers. After it is all laid up, remove excess epoxy leaking on
sides, take the top part of mold, put it on top of the other part and apply
hand pressure to get excess epoxy out, carefully making sure your material
stays straight . Wipe excess and then tape top part on bottom part keeping a
good tension all around. . After, put a weight on top and let cure.

Next morning, remove carefully gear from mold. After, put masking tape on
inside of gear, trace the pattern you want for your gear, then, with band
saw, cut to desired shape. Don't forget to use a mask CF dust is harmful for
your lungs. Finally, you finish trimming on strap sander or by hand. You may
also sand lightly and put a final coat of epoxy to get a nice CF look. You
may also paint it, what i did. For added strenght, you may also cook the
gear for curing at about 150 degrees F for 3 hours. Dont use your house oven
for that. A box with a small heater inside will do fine.

My original gear on Sukhoi was 22 ounces. My replacement is 12 ounces, a 10
ounces weight saving, and it is even stronger and more flexible. Total cost
in CDN $ is about 25$.
3 hours of work for a good weight saving.
Hope it helps.

Richard Biron