Woudln't it make sense to just draw the gaps as thick lines? More like this, but in pretty and with your great helper lines: https://i.imgur.com/TFrEDxT.png htt

Woudln't it make sense to just draw the gaps as thick lines? More like this, but in pretty and with your great helper lines: https://i.imgur.com/TFrEDxT.png https://i.imgur.com/TFrEDxT.png And maybe a button to lock the helper lines?