Finishing the Boxes
Once you've built your own set, finishing the surface with a paint job can be the most enjoyable part of the project (especially if you're like me, and play the game miserably). In addition to the State of Ohio Flag design shown above, the sky is the limit as to the designs one can add to the box.
In general, after thoroughly sanding the surfaces, I seal all screw heads and imperfections/holes in the plywood (especially along the ends) with a filler/sealer material (DAP, etc.), apply a coat of heavy exterior primer (KILZ or similar), and then apply 2 coats of the desired top coat (semi-gloss is adeqate). As long as exterior grade materials are used, it is not necessary to use a polyurethane finish (plus, this may likely make the surface * too * slippery - it certainly will yellow white surfaces).
NEW! Another finishing option: If you have access to a vinyl decal maker, you can actually affix that to the top of a deck, using any design that can be duplicated. Then, use Evercoat brand Table Top Resin (a 2-part epoxy resin) as the sealer (the manufacturer states one coat of this is equivalent to 50 coats of polyurethane). This isn't quite as slippery as polyurethane, but works very well, and protects the otherwise fragile vinyl indefinitely. Makes for a truly beautiful finish! Note, Evercoat is in the process of launching a new brand of this product line. Until then, you may have difficulty finding it. ACE Hardware and other such stores typically have a similar Bar Top or other table top finish. Essentially, it must be a 2-part epoxy, and should pour on. Follow the instructions; bar top finishes look wonderful, but take patience (though the surface is only workable for about 30-45 minutes).
Note on such finishes (especially the epoxy): they tend to yellow from UV exposure. The best way to avoid this is to limit the use of WHITE paint under the clear coat. Colors do not tend to noticeably yellow as badly. Some finishes contain UV filters, but they also tend to NOT be clear.
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