Just like when you made your silicone mold this is another messy little job.
There are gloves for fiberglass work so you should get a pair or two.
Wear old cloths, the resin will never wash out.
You should get some thinner to clean your hands with - the gloves will help a lot but you will end up with some on your hands no matter how careful you are.
By now you are probably wondering if you want to make your own mold.
When your first concrete or hypertufa casting comes out you will know.
It is a great feeling to see the results of all the work you did and you may decide it was worth it.
That is when you should start planning your next project.
Go to a place that sells fiberglass - you can find them in the Yellow pages - to get the materials you will need and be sure to get extra, you don't want to run out once you have started.
You can estimate the amount of roving by wrapping your mold in a piece of cloth and then measuring the cloth to see how many square feet it is.
The fiberglass supply guys should be able to give you an estimate of how much resin and hardener you will need if they know how much roving you are going to use.
Don't forget to tell them you will be doing 3 layers.
There will be a layer of fleece and two layers of roving.
Buy roving, not cloth.
The cloth is for jobs where you need high strength.
You will not need it for your cover.
You will also need three or four 2 inch paint brushes.
On the way home stop at a fabric store and buy enough of that stretchy fleece to cover your mold.
Now we begin...
Cut the fleece so that it fits the mold fairly well.
If you want you can glue the fleece onto itself with fabric cement here and there.
This is not usually necessary but you may have to.
Now mix the resin and hardener - be sure to follow the instructions exactly - and paint it onto the fleece.
Soak the fleece and push it up as tight as you can to the rubber mold.
Try not to have any air pockets between it and the silicone mold.
While you wait for this to harden you can cut your roving into strips one or two inches wide and about a foot long.
I don't make the any bigger than this because it makes them to hard to use.
Lay them out somewhere handy and if the fleece has hardened you can start the second step.
This is the real messy part.
Paint some mixed resin onto the fleece and pick up a strip of roving.
Put the strip onto the fresh wet resin and smooth it out as best you can, but don't worry if it is not perfect.
You are doing this for strength, not beauty.
Repeat this until your mold is covered with a layer of roving.
You will need to work quickly here so you finish before the resin starts to set.
If it starts to set throw it away, you will have to mix more.
You cannot use it once it has started to harden, don't even try.
Now that you have a layer of roving on you can paint it with some more resin and build up at least one more layer and cover with a coat of resin.
Let this all set up and there it is.
The ugliest looking mold on Earth.
But inside lies a thing of beauty.
If you have done a good job it will last for many, many pours and some beautiful concrete and hypertufa pieces will come out of it.
Go ahead and make one! Who knows, you may be one of the rare people who actually enjoy doing this.
Once you have it done I'm sure you will enjoy using it and will be something that you can be very proud of.