When using a spirit level (aka bubble level) to mark mounting points on a wall, you almost need three hands. The Levelmarker 2.0 is designed to address that problem, by combining level-holding and mark-making in a simple two-handed job.
Ordinarily, if you're installing a shelf on a wall (as just one example), you start out by using both hands to hold a spirit level on that wall at the desired height.
Once you've got the device perfectly horizontally level, you then have to let go with one hand so you can draw a line and/or mark the locations of the two screw holes on the wall. It's certainly not an impossible task, but it can definitely be awkward.
That's where the German-designed Levelmarker 2.0 comes in.
The setup consists of three parts – two marker tools and one "stopper" tool. All three get clamped onto your existing third-party spirit level so they can slide along its length. Both marker tools incorporate a spring-loaded pen cartridge which points at a right angle towards the wall.
You start by determining how far apart the two screw holes need to be, after which you place the two marker tools that far apart from one another on the level. The stopper tool is placed exactly half way between them. All three tools are then tightened down so they stay put.
Next, you hold the level by each marker tool and place it against the wall, so that the stopper tool is located where the middle of the shelf will be. Once you've got the level perfectly straight, you just push on each marker tool's pen cartridge – with the hand that's already holding it – so that it marks the wall.
The replaceable pen cartridges can be pushed up to 20 mm, allowing them to be used on surfaces which are rougher than completely smooth, flat drywall. They can also be flipped around to sit straight in line with the rest of the marker tool, which can then be utilized as a plain ol' pen when not mounted on the level.
The Levelmarker 2.0 is currently the subject of a Kickstarter campaign. Assuming it reaches production, a pledge of €13 (about US$14) will get you a setup – that's 27% off the planned retail price.
It's demonstrated in the following video.
Sources: Kickstarter, Levelmarker