Hush, Hush!

I've finally finished my 'top secret, can't say anything or I'll have to kill you' project. As you can see it's very technical as it involves fancy rulers and such. I don't know why it has taken me so long to actually get it done, I took procrastination to the next level on this one!
Can't say who or what it's for, but you can probably make out what it is...but keep it under your hat *eyes dart around* it's very hush, hush!