Hobbyzone Waterline Marker, with the use of waterline marker tool you will be able to make a straight line on the same height. You just need to set the desired height and then move the tool along side of the hull or something different where you want to make straight line.

Tool has adjustable height between 45mm - 225mm (measured from the base)

If the height is too small you can put the tool on some other object to add height.

This set does not include pencil. Thanks to the special shape of the pencil holder you are able to attach pencils of different size and shapes.

Set consists of perfectly cut elements and assembly instruction. Assembly is not complicated and for permanent assembly of some elements wood glue will be needed.