Hm, I haven't trained them for a long time, I always had the feeling that I could do it anyway if something has to be done (normally I'm not that confident, but when it comes to my skills I am^^). But since my ISTP friend moved in we have a little project, because I did nothing with my flat for over three years, just established my room and had no curtains or lampshades or similar things installed. So, since he moved in we have built a lot of things and it looks damn nice now and I see, that I would have completely failed without help, so I told my friend to practise with me and it really helps and is fun to do so, also because ISTPs have a very amusing but strange way to manage things.
Is there something specific you want to train or just your "all day" mechanical skills?