Reddit mentions of Color Drawing: Design Drawing Skills and Techniques for Architects, Landscape Architects, and Interior Designers

I've found this book really helpful for different techniques. They cover hand drawing and rendering techniques as well as some tips for how to tweak things in Photoshop to achieve certain results.

I found a copy at my library and eventually found a cheaper used one to keep on hand for reference.

http://www.amazon.com/Color-Drawing-Techniques-Architects-Landscape/dp/0471741906/ref=sr_1_1?ie=UTF8&qid=1333056540&sr=8-1

Nice work. if youre interested in improving your hand rendering skills check this out. some of it is pretty tough, but just duplicating it will make you better. lots of different techniques in there.

http://www.amazon.com/Color-Drawing-Techniques-Architects-Landscape/dp/0471741906

A lot of suggestions for Legos. I may be wrong, but that seems a little juvenile for a 12 year old girl.

I would suggest getting her this book: https://www.amazon.com/Color-Drawing-Techniques-Architects-Landscape/dp/0471741906

Then, when you take her to look at architecture, you can sit for a while and do a sketch. This doesn't just help practice sketching, but also develops an appreciation for architectural details through observation.

Perhaps buy her a book of Frank Lloyd Wright drawings, most of which were done by Marion Mahony, who is responsible for the Wright "style" drafting. They are great inspiration. A short (15m) documentary titled "“A Girl Is A Fellow Here”: 100 Women Architects in the Studio of Frank Lloyd Wright" covers Mahony, who was one of the first woman architects licensed in the world. It can be viewed here: https://vimeo.com/5494646

I agree with others who have suggested getting her into shop work, building things is very fulfilling.

Good luck.