Pls see my reply for the core thickness on the above thread.
The 155/50/1.5 cm Paul.plank is less than 2.5kg if remember well. Impossible to bend by hands. Hence, 100g FG bias on bottom and 200g UD on top will make it really stiff.
I have a FS Rad 4, almost same dimensions as my DIY, FS has closed cell as a core for half of the board, by length.
My full Paul. wood board is lighter. This means the same "door" board would be also lighter simply coz of less FG and epoxy:)
That said, for double the board size, >1kg epoxy would be needed with a CC foam.
Same in wood = 600 grams.
Remember, the total cost for a TT DIY is $30-40. That's material cost with a FG for the shop quality hand made board. Some ppl are buying it coz of the wood grain, looks bloody fantastic.
Same production "hand" made board sells for €1000 or more.
The topsheet price 100m from the factory is €400. That's ~€10 per board. Cheap.