I use dots of nail polish to make things. I have a single hole throat plate for my Janome. I forgot it was on several times and broke a needle. I could really screw up my machine that way. I marked The edges with bright pink nail polish so I would remember it was on. Also my creative grids ruler that is 6 1/2 inches drives me nuts. I keep using the wrong side and screw up my cutting. I marked it too.