You'll find that using
Luan is the cheaper way to go for several reason. The biggest being labor. Soft covering flats, even if you use
Gaff's technique of mus over
luan, takes quite a
bit more time as you have to cut the fabric, attach it, then size it, there is a lot of waitning inbetween steps.
Looking at your
rendering, it should be a very simple matter to construct this pro from standard "studio" flats. I prefer 1/4"
luan as a covering for long term use, and for flats that need to stand up to some actors chewing on them. In the case of this pro I think I'd elect to go with the 1/8"
Luan.
MDF can be used but if you are going to be doing extensive painting, it will buckle and
bubble, unless you have framing every
foot or so. 1/8"
luan will allow you to put your toggles on 48" centers, this will save you money and weight. I can post a drawing, if you need it, to show a good way to construct those curvered areas so that you don't lose their depth. How thisck is the retuen on the interior
edge?