A 2.7 mile long straightedge (kickstarter.com)

In case anyone were wondering, gravitational lensing would only account for 1.6030569323305754e-13 m or 0.16 picometers of laser deflection when the laser would be tangent to earth and the ruler is extended from that same point.

Deflection approximated by:

    tan( G * mE / (r * c(air)^2) ) / 4345 [m]