I want to try and create a wooden water tower for a production of Urinetown. Looking something like this: http://www.nrhc.org/img/nrhc/water-tower.jpg I think I could figure out the structure (though if anyone has any tips that would be great) but I don't know what to put over the surface!
I don't know if luan will bend enough to for me to cover the surface if the diameter is only 6' or 8'. Is there anything I could use that would work easily?
Luan can definitely be bent to make that radius if you're careful about it. Make a plywood ring at least every 2' and add as many 1x3 ribs as you can to provide gluing surfaces and support. Start on the upstage side of the unit and give yourself a good 2" or so of attachment surface to start with. Place your sheet horizontally so you are bending in the direction of the grain (if your tower is more than 4' tall you'll need to double up plywood rings at 4' to give you a full seam catcher). Be VERY liberal with your glue and use lots of clamps or extra hands, and instead of just using fasteners through the luan, add a piece of 1x2 on the outside and screw through it with 2" screws through the luan and into your framing (you'll remove this once the glue dries).
Proceed slowly and carefully around the rings, adding a 1x2 with screws every time you pass a support rib. Add extra support ribs wherever your seams end up hitting, and add extra 1x2 screw pads to help keep them in place. Again, LOTS OF GLUE! Once you've made your way all the way around, carefully cut your luan to fit (or leave it a little long if you want an overlap at the back) and finish with a final 1x4 to cover the seam (this can replace the initial 1x2 piece that held your starting point. You could start with 2 2' pieces of 1x2 and replace them one at a time with 1x4 to cover the seam at the end). Give the glue plenty of time to dry, then pull the screws and take off your 1x2 boards. Putty the screw holes, or drive new screws into them just barely countersunk into the luan, and paint! I used this technique to bendluan around the complex curves of the top of a unit I created for a traveling youth circus last month. Some sections had a radius of about 1'-6", so your 3' radius should be fine.
For the top, ramboard is going to be a far simpler way to go than the luan. It might work physically to make a luancone, but you're going to be cursing your design every step of the way. Build your frame, cut your seam, put it in place and staple it down. Maybe give it a thin coat of joint compound and texture it to look like rusted metal, or give it some woodgrain texture if you would rather.
Consider a cheap sheet vinyl flooring, bottom side out. The felt backing is paintable. It will bend smoothly over the framework and even work for the top. A flooring store may donate a piece.
I'd forgotten about vinyl flooring. I, too, have used it for curves. It's really great if you're working on organic shapes. This is a tree stump I made for a show That has about a 4' diameter. The upper is vinyl flooring and the lower is chicken wire and lightweight muslin. ***Apologies for the poor early-camera-phone picture quality.***
