re: Box clamps box

1:4 doesn't matter, in fact the angle on the 2 sides of the joint don't have to match, you just have to cut the tail or pin, then mark up the other to match, as long as it fits the angle doesn't matter, you could do 1:3 on 1 side and 1:20 on the other, might offend your sense of OCD but it work's fine - in fact you can get some nice effects by varying the angle on the dovetails as you roll up a board.

If you want 1:4 specifically, mark 1 Inch in on a board, 4 inch down, use a bevel gauge to join the 2 marks and you have 1:4 - I'm fairly sure you will have something that can make that angle measurement much more accurate than anything I can do.

I never did the 30 days of dovetails thing, just made something with a fair amount of dovetails in - the ones I did last are a lot better than the ones I did first on that project, so I reckon it's a good idea if you have the time.