< but I couldn't figure out how to make a wall say 15 feet or make things to a specified sizes (in Sketchup)
Depend of Unities
Just Type 10,200 (page right bottom) if you want a rectangle 10m *200 m and press P (for push) and type 2.4 if you want 240 cm hight :)
But you can make the same with the mouse :)