Infusion would obviously be my first choice if money was no object, but this will be a budget build which is why I am aiming for wet-lay and vacuum bag.

I was intending to use foam as it will not add as much weight as soric due to it not absorbing extra resin.

If you already have a vacuum pump (capable of full vacuum) then the extra cost of going to infusion would probably be offset by the savings in resin
(You will get a much better resin to fibre ratio, probably even with the Soric)  Of course the Soric is a bit more expensive than straight foam core.

You could use cheap floor cork .. I've done some tests on that .. It will give you a lighter panel than the Soric, and much cheaper - You may even be able to use it with hand layup-
It has very low resin uptake, definitely lower than Soric.

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