I am going to build a couple top feeders from the plans on the site. Those of you who have built them: What did you seal the inside with, if anything, and how have they performed, leak-wise?
Caulk
I've built a few. I use Gorilla glue on all the joints and two coats of polyurethane to seal the wood. One feeder is three years old and has not leaked a drop.
John
Deck screws & tightbond 3 for the joints. Beeswax & paraffin for the entire inside. Including the floating grates.
(hint) stick a galvanized finishing nail in each grate; if you make that kind. Use it as a handle when you're wearing gloves
My neighbor bought a wooden one that got moldy inside very quickly. The black-green mold that gets into the wood. I painted the inside of mine with the hot wax mix. Not just where the syrup is in contact with the wood but everywhere inside. Year and a half later no mold and it looks like new. Nicest thing is it can be rinsed when it gets dirty.
No leaks
I also coated the inside of mine with paraffin wax. Works great, although a little slow without a dip box.