piercing the holes for bag feet through the bag base
Fellow-Brits of my vintage will remember fondly Blue Peter teaching us to make holes in the back of paper by pushing a pencil point through with a lump of modelling clay underneath. Then there are those who favour poking the blades of a nice sharp pair of scissors through their chosen material. Well, I can guarantee much better control, and less potential for broken pencils/clay-covered fabric/severed fingers if you actually use an awl to make a hole.
a dab of fray check to stop the fabric fraying, and you're good to go
(yes, I need a new cutting mat)
Not just for poking holes in things, a nice pointy awl is invaluable for guiding fiddly things under your machine foot without risking your fingers under the needle. Digits tend to be fairly essential in sewing, so it's always a good idea to look after them. If you don't already have one, you really need one.
And did you know that the cockney rhyming slang phrase 'a load of cobblers' (meaning 'a load of rubbish') comes from the humble awl? Neither did I, but I do now.
So what sewing tools do you think are essential? Always keen to know if I'm missing a trick!