Thread: Please help me make love...

Judging from the pics, weight is potentially a big issue.

You could make them out of 3/4 inch or thicker exterior grade ply, but they would be heavy and perhaps difficult to transport.

My initial inclination would be to make up light framework from something like Surian cedar (light, but reasonably stiff and not too expensive) and to cover that frame in the thinnest exterior grade ply I could buy.

The other issue is stability in service. Made as per the above, a stiff breeze might blow them over ... not a desirable effect. Even made in 3/4 ply, the letters would not be stable. So, that issue needs to be conquered. Perhaps you could make the base board for each letter larger, to form a base, and to make the base board out of thicker, heavier material. Your other option is to have some sort of bracing legs, but my guess is you really want free standing letters. My best solution so far is to make the bases bigger and to glue a plastic jerry-can to each base. If they were filled with water after being erected, that would likely keep everything reasonably stable.

Getting a waterproof finish is not tough. If it is suitable, I'd be inclined to use a waterbased exterior paint over ply. But if you want high gloss, enamel paint would do the job. Remember, the higher the gloss, the better the preparation must be to eliminate blemishes on the surface. MDF is a great substrate for paint, so you may wish to consider thin HMR MDF over a cedar or similar frame. MDF is also a cheap option.

Let's see what else the brains trust comes up with.