Why would you ever futz around with a bubble level when you can find a straight line with a LASER? <Inception horn>
Tacklife’s self-leveling cross-line laser mounts to any wall, and projects a perfectly straight horizontal and vertical line in either direction for up to 98 feet. It’s currently listed on Amazon for $110, but promo code EIC2ZXZR will bring that down to just $60. You don’t need to be a laser technician to know that that’s a great deal for anyone that enjoys home improvement projects.