What length would you estimate for the two horizontal boards in this picture? If a coffee mug is 3-3/4" tall, I'd estimate 32". Then again, when I estimate these things, I get the opportunity to build them twice.
Looking at picture, the inner of the two mugs on either end is even with edge of vertical member. Outer mug looks to be about 1/2" past edge of vertical member. Wood looks like 1 X 6 to me, meaning it's 5 1/2" wide, so mugs are spaced 6" OC. With half a space on each end, that makes horizontal member 30" long (3 + 6 + 6 + 6 + 6 +3 = 30.) Remember you can take my opinion and $0.68 and get a senior coffee, just make sure you have the $0.68. Shows what my opinion is worth, doesn't it?