This is a simple Heat Exchanger. I haven't printed it. So build at your own risk.
My plan is to use regular kitchen aluminum foil as the membrane between layers. I want to keep it as thin as possible. To make the heat transfer easy.
There are holes for nine guide rods, but you can use as many is you need. i plan to glue the aluminum to the core frame and slats.
The large holes should fit 80mm fans or duct flanges I plan to use 3in ventilator ducting.
The guide holes in the core are 3mm.
The holes to hold the lid on are 4mm.