Scales for an archaeological dig. Or a crime scene. Or, if you're really lucky, a medieval crime scene. The big squares probably want a few of them making. You can number them with a whiteboard marker to link up with your field notebook. Make these from 2mm white acrylic. If they're for heavy use, acetal (Delrin) is a bit less brittle.Fairly simple bit of laser cutting, with an ink infill afterwards. The grey and black areas are raster engraving to texture the surface so that the ink sticks. Ideally the black should be black and the grey should be an 18% photographic grey (look up "Kodak gray card" for an explanation). This is an exposure scale rather than a size scale, with a standard mid-range colour for printing an accurate rendition of the scene. NB - I haven't got this to work yet - the search for "grey Indian ink" or functional equivalent continues. The line engraving (blue on the drawings) was vector engraving on my machine as this is quicker, but you might find that the lettering is easier as more raster engraving. Everything fits onto half an A4 sheet. CDR files are the original master, but there's a PDF version too. To colour the lettering and the shading, use artist's Indian ink. Wipe this on with a cottton bud, over all of the shading (don't miss any). As it dries, wipe it off gently with a cotton wool pad (makeup removing pad). If it dries too much, use damp newspaper and rub harder! For any ink infill work, it's important that the sheet used is unscratched on the front, so look after it in storage.