Reddit mentions of Bon 32-500 1 Pound Bag 3/4-Inch Anti-Crak Concrete Fibers

Yeah, I did a few test batches that were in the 12"x12" neighborhood. I used melamine for the forms and largely found this Ask This Old House video to be very helpful (although I didn't use the spray method for the initial coat). Key points that I used and learned:

• Using caulk for a roundover works really well. Use a high contrast color between the mold and the caulk so that you can clean up excess caulk (e.g. if using white melamine for the mold, black silicone caulk is perfect). You might be surprised how much detail the concrete picks up from stray bits of caulk that you left in the mold.
  
  • Tools like these modeling tools are great and give consistent roundovers
    
• As in the ATOH video I linked above, I used glass fiber reinforcement instead of using a metal mesh. Fwiw, I used this stuff: https://smile.amazon.com/32-500-4-Inch-Anti-Crak-Concrete-Fibers/dp/B000CODWAE/
  
• Wax the whole form with paste wax before applying caulk. It makes the excess caulk peel away SOOOOO much easier
  
• Add extra support to your form if needed. Concrete weighs a lot, and you don't want to have a curve in your countertop just because the mold was sagging under the weight of the concrete
  
• It's worth the effort to get your mold nice and level. It also needs to be stable enough that it's not going to bounce all over the place as you hit it with a mallet to get rid of air bubbles.
  
• For the form, I used screws to secure the walls to the main board. Drill generous pilot holes so that the screws pull the walls tight. Countersink the tops, and use some tape to cover the screw heads (I used painters tape). Covering the screw heads makes it easy to remove the screws after the concrete has cured and it's time to open the form. If you get concrete in the screw head, it's not the end of the world, but it's a pain to deal with.
  
• Plan ahead and rehearse your order of operations before you start anything that is time sensitive (primarily when it's time to pour the concrete). Do you have enough water? Enough concrete mix? Are your tools available? If you're mixing with a battery operated drill, do you have charged backup batteries? Dust mask? Screed that can span your mold?
  
• The mix especially for the part that will be visible will be soupier than you might expect if you've used concrete for things like fence posts. It being loose will allow the air bubbles to escape due to vibrations.
  
• I found a firm mallet worked better and was less exhausting than a larger rubber mallet. I've seen people on YouTube use power tools like random orbit sanders or reciprocating saws, but I did not have much success with those.
  
  I think that's pretty much everything. Doing a couple test pieces will teach you a ton. Have patience, have fun, and good luck!

Out where I live, we have moved away from the rebar for light duty applications, such as patios and driveways. Crack control is now done with "kitty fur" and control joints:

https://www.amazon.com/32-500-4-Inch-Anti-Crak-Concrete-Fibers/dp/B000CODWAE

We mix this thoroughly into the concrete, and the fibers help to prevent cracking during the curing process, and afterwards. They are available in many different thicknesses and lengths, depending on the job:

http://usa.sika.com/en/solutions_products/Construction-Products-Services/Concrete/concrete-reinforcing-fibers.html

Call around, and see if this is available in your neck of the woods.

I would look into quikrete 5000 which can be bought a Lowes for $5-6 a bag and just add fiberglass shards for added strength. That's what i plan on doing for my bathroom vanity.

https://www.amazon.com/32-500-4-Inch-Anti-Crak-Concrete-Fibers/dp/B000CODWAE/ref=sr_1_1?ie=UTF8&qid=1491533180&sr=8-1&keywords=fiberglass+fibers

Can i just get some normal concrete from a big box store and mix in glass fibers?

Im considering this for the concrete:
https://www.lowes.com/pd/QUIKRETE-ProFinish-Crack-Resistant-80-lb-High-Strength-Concrete-Mix/3026899
and
https://www.amazon.com/gp/product/B000CODWAE/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1 for my fibers