Reflector ovens, like dutch ovens, take a little practice but they are not difficult to use at all. Baking on a campfire is great fun and well worth the effort. Here are some plans and commercially available ovens to get you started;

Here’s a home-made oven – see more pictures and directions here
Here’s a lightweight, home made, oven. The sides are aluminium, the reflector and tray are titanium and the ‘nuts and bolts’ are spokes. No plans available but there are more pictures here
Old Scout Reflector Oven crafted of aluminum and weighs only 24 oz., using an innovative tab and slot construction to slip together quickly and securely.
Large Canadian Aluminum Folding Reflector Oven Oven measures 21″ x 15″ x 8″ open, and 21″ x 15″ x 3/4″closed
Sproul Reflector Oven Hand made in Maine
Svante Freden – Reflector Oven A super lightweight reflector oven made in Sweden, approx. 10 x 13 $79.95
Kraiker’s Baker PDF file Plans for a simple top opening reflector oven 14 x 12 x 12
Oven Plans from Kayak2go.com PDF file Top opening, about 7 x 9 x 12
Biscuit Oven non folding – 16 x 14 x 10 crafted by tinsmith Bob Bartelme $75.00