• When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

Making a piece in Fiberglass

sam dupont

FBBO Gold Member
FBBO Gold Member
Local time
4:47 AM
Nov 9, 2020
Reaction score
Never worked with latex molds. This is the first coat, and the second coat is setting up in the cup. Planning to make a fiberglass dual quad air cleaner for my experiment.
I used Smooth-on 25 over their sealer, then Mann 200 Release.
I have a few things I would like to make, so I'm starting with a no pressure piece. If it turns out: bonus

2nd coat
Last edited:
Cool project. I will be following. Please keep us posted on the results!
Are you planning on using polyester resin or epoxy?

I think epoxy. I sensitized myself doing a big fiberglass job. I finished and then noticed the ground was like a trampoline. I get dizzy just writing about it.
Have fun with that project. You might learn a few new swear words. :)
Not sure why you're using a latex mold, now you have to build significant support for it to maintain its shape. You could have just made the mold with a couple layers of fiberglass and and for something like that it wouldn't need any additional support structure.
I use to make copies of wing tips after modifications were done for the use of a stall kit. It was a process. Take a glass mold , build a structure on the mold to keep it rigid. Spray the inside part of the mold with gel coat. ,I have a chopper gun where it runs a strand of glass mixes with the resin and hardner Quite a process.

for some thing that small like your doing. A two part mold where you can form the material around the item. Leave sit for a couple days and pull from the original item. And it is reusable. You can brush resin in tear the matt into frayed strands and start building up usually two layers. After drying pull apart then make a second one.
I have a few molds that are ready and I don't want to risk damage to their finish, so the dual quad lid is a latex guinea pig. Fiberglass wants to bond to things so much, it scares me.

In a couple days the latex will be cured and I will pour plaster of Paris around it. I have some gel coat from a local boat shop. I don't have catalyst, will have to figure that out.

There was a place in town that built porta-potties. They would spray stuff with a chopper gun. Their prices were pretty reasonable, but they folded, don't know why. Somebody must have come up with a cheaper
Fiberglas portapottys would be labor intensive compared to roto molding!

i don’t see any “draft” on that part you’re doing - gonna be a bitch getting that out of a one piece mold !!
Fiberglas portapottys would be labor intensive compared to roto molding!

i don’t see any “draft” on that part you’re doing - gonna be a bitch getting that out of a one piece mold !!

getting it out if you have mold release in there use air in a crack it should pop out the casting.
Try this stuff. You may need a couple. Buttt…


I did the mold then pulled it away from the original. Then made a test piece from the mold , seemed to work then made the actual item.

Fibreglass resin produces the same heat when curing.
Last edited:
Popped right out. I'm happy so far. This is just a test and I need a pair of air cleaners for my low deck dual quad. Now, I'm off to learn about composite materials.
So if the plaster was poured over the latex then the plaster will not make an accurate copy of the original - right ??