Lego creations

Outside of Meccano which was my favourite engineering based toy, lego was the second best because provided you avoid the misguided souvenir kits, your only limit on what you could make as a child was your very own imagination.

Even running out of parts could be tackled buy either buying whole new sets some of which may contain things like electric motors or bundles of bricks in whatever form and colour you prefer. 

Unfortunately the very set I had as a child and all the extras got taken away by folks in my mid teens for some reason or other but I do long for a 'proper' one.