I'll second the 9x12 Patent Etui being small as I have two, far less than it's rivals but while the smaller formats are still ahead of their rivals it's by a smaller margin.
The beauty is that 9x12 sheet film is readily available as well plus roll film backs are easy to find.
Here a Patent Etui and a Crown Graphic plus my 6x4.5 Ikonta

Should add that the Crown & Etui both have 135mm f4.5 CZJ Tessars, the Etui's is about 10 years older and a far better lens, (The Crown had a redesigned 1932 Tessar and the glass is softer less contrast with ageing).
Attachment 34698
The Patent Etui is light but rigid, I'm in the process of fitting a modern lens to my second camera as I prefer coated lenses.
Ian