When pouring use a couple of craft stick and slowly pour over them and into the mold, it'll help take out more of the bubbles. Pour about to 1" for 1/2A props and 1 3/8" for larger and no more. I've found that 3" c-clamps are alot cheaper than the larger and you'll need a few, four for small and eight for those 13" stunt props. Good mold material will not crack at this thickness.
  Now let it stand for the required cure time, I let the F.C.C. sit for 24 hours before the box plates come off. Now pull the location pins out and using a chisel carefully work a corner until loose and then the opposite corner until the base plate comes off, do not twist but pull straight off. The mold top and prop should come the base together. If the prop sticks to the base remove it and reposition it into the top half of the mold. Now take a file and take the sharp edges off , it'll cut without you realizing. You'll note that some of the paint come off with the mold top, don't panic, it'll scrape off with your finger nail or a craft stick. You'll need to use a hobby knife to detail near the prop , scrape it and cut off paint around edges.  PVA will stick to whatever you layup on it so, try not to distrub the mold top too much, even the moisture on your hands will melt it, hold with a paper towel.
  Photo to the left shows the top mold with pins reinstalled and PVA'd, top, pins and sides. Use some putty on the tips of the prop to smooth them in otherwise, when the top half is poured and is curing, it will snag the tips went it shrinks and distort. For the longest time I had a problem with the tips being thicker than the plug, this solved it.
  Grab the box plates and wash them with warm water and recoat with PVA. It seems that resins soak past the PVA and causes the new coats to bead, don't wash the top half of the mold at this time. After the PVA has dried, assemble the box around the mold top, don't forget to tape the cracks again and pour the bottom half.
  I'll bet your getting impatient now, wait for the time it needs to cure. Now remove the box plates and pins, let it soak in warm water for about 1/2 hour, this will help to break the two halfs apart. Now carefully take a chisel or or sharp tool and at one corner break it apart. The prop plug should be stuck on the bottom half of the mold, it's being held by the mold compound encompassing the edges of the plug. The putty at the tips  should make it easier to pry the plug out, try your fingernail first then a piece of wood, some mold edge breakage may occur.
  Wash the halfs and admire your work for a while........................................
We must now do some prep work before we can mold. On a belt sander, knock down the corners of both half mold surfaces ( check out the picture ), this helps prying the halfs apart after you've layed one up. Using a 1/4" carbide burr, non-endcutting, cut a trough on the top half of the mold, at the tips for the fibers to hang out, putting the prop in will help. We need to sand the bottom half of the mold to remove the sharp edges of the prop outline, you just want to take the sharpness out not the whole edge. This outline will help keep the fibers contained when you clamp the halfs together and give the reference of the prop outline when triming after you've layed one up. Check out the top half for any sharp edges and take them down, you may find some them around the hub area.
  Start preping by waxing and applying two coats of PVA. Wax the shaft pin seperatly and install then PVA, don't forget to do the sides to help keep the sides from building up excess resin when layed up.
  Time to layup, this is trial and error, experiance helps here, cut some carbon unidirectional carbon fiber, the first are 4 x 7'', 4 x 3", 4 x 1", and 4 more at 7", this is also the seqence which we will layup. You'll have to figure the right seqence for your own application. Don't forget the alignment pins. You'll also need some carbon chop to fill in the corners on the top half of the mold which is the side you lay into first, add the fibers, add some chop to the bottom half in the corners and coat the surface, mate the halfs and squeeze together by hand before going to the clamps. When  using the clamps don't horse them! Start near the pin and close down easy, work from the center out until the mold halfs are seated.    
  Now that you've waited for the appropriate amount of time for curing based on the resin your using, unclamp the mold and remove the pins and using a hardwood wedge, break the halfs apart. To the right is a picture of the prop I molded, note that some fiber did squeezed out but the flash is only .005" thick, which is acceptable. When you mold yours and an excessive amount of fiber is in this flash and it's thick to boot, you'll have to modify your layup.
  To trim, get a fine pitch saw and cut the ends off and using a curved sissor, trim the flashing close to the outline. Use some metal working files to take it to the edge of the outline, a half round second cut works well for this.
  The resin I use is Epon 862 with Epi-cure 3234 from Shell Chemicals. Whatever resin you use make sure it has a low viscosity and is somewhat heat resistant to keep the hub from mushrooming. The lower the viscosity the more fiber can be used, the stronger the prop. Good luck with your own project.