Hi
I'm going to make fiberglass fins (for freediving) with Epoxy infusion. I have made several tests to achieve a smooth surface on both sides. I have tried with peelply, it gives a rough surface. I have tried a silicone plate, it does not give enough epoxy flow and the epoxy tries to find roads that are not planned. I want to achieve a process where I can make two smooth surface at the same time. I have attached an image on which they have made an setup that I would like to make, but I need little help ....
Are there any suggestions on what their setup is? I can not see peelply is being used on the image. And what purpose is the string / rope that is at the edge of the mold?

I think the peel may be there, it could be the white material.
Not sure about the pink layer there, I think it may be a layer of release film.
I use a rope for the perimeter vacuum.

Thanks for the answer. If peel ply is used, it will leave a rough side and the fins must be made of two laps to prevent the rough side. I do not think they are made of several laps, otherwise it will be too expensive and time consuming to make commercially. I have attached a picture of how they look (and they have smooth surface on both sides)

Please come up with suggestions on how the setup is made, as I run out of ideas soon.....

You could have a single sided mould and set up a vacuum infusion with a thin flow medium within the laminate. On the backside of the laminate use a sheet of mylar film which is a super glossy smooth plastic film that is quite firm. (try and find a sailmaker for it) Then you infuse through and in-between the mould and the mylar film.

Or you need two rigid mated moulds which you can set up a through infusion too.