This is how I build the frame for the deep water culture (DWC) unit for my aquaponics system.
One thing I learned when working with varnish is I need a lot of thinner to dilute the varnish. The way I do it is by pouring some varnish into paint tray, mixed with some thinner, and paint a thin layer on the wood. However thinner evaporate quickly and the varnish eventually become thicker again, so I have to regularly add thinner to the varnish.
Not an easy task to do, some of the wood are bending so need to use more force to screw at the right place. Some are hard wood, so when I drilled it continuously, the drill bit become too hot and break eventually. If I use small drill bit size, it’s harder to screw, and some screws couldn’t go in, I had to cut them and replace with nails.