In the past - I had a prop making studio for many years. Was difficult hiring qualified hands as everyone wanted to be part of the 'fun'.
Not many could meet up with their claims; then it dawned on me to setup a skill test as part of the interview.
So I setup a workbench with various power/air/manual tools, parts, pieces, shapes and other related items, then had them perform various tasks with each.
In brief, I could see if they had any experience, the speed, confidence and basic problem solving skills; not to mention, the motivation to learn.
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So would it not be helpful to setup a similar scenario, whereby setting up a sequence of short tests, both analogue/digital - relating to both machines and software knowledge?