The Lightboard that I make (and use) is 40 inches wide, 30 inches high, and is about 7 inches deep.  The side legs are 16 inches.
The working surface of the glass is 31 inches x 16 1/2 inches.
It weighs about 45 pounds. Most of that is from the weight of the glass.
It sits comfortably on my desk.  I can move it forward and back if I need more space on the desk. The keyboard fits underneath, so it doesn’t interfere with using the keyboard or the desktop. The legs “straddle” a 27″ iMac, so I can literally slide it ALL the way back to the screen (but I never do, because it’s not necessary).
Here is the Lightboard on my desk:
The artwork behind me is “Hot Chocolate” by famed Deaf artist David Call, who lives in Livermore, California. He makes linocut artwork, and then prints limited editions. You can learn more about him and other Deaf artists at the De’Via artist group on Facebook: https://www.facebook.com/groups/deviacentral/