You will need:
Meccano strips/plates of your choosing
Length of chain or chain necklace
Jump rings of varying sizes (mine ranged from about 6mm to 12mm)
Jewellery pliers and cutters
This is a really simple DIY. You're basically just constructing your necklace a piece at a time until you have your desired look.
It's a good idea to lay everything out first, making a design to follow so you can see how everything is likely to look once finished, making changes along the way if things don't 'sit' or hang the way you'd like.
Then it's just a case of connecting the pieces together using jump rings.
It really is as simple as that.
There are loads of things you could do with Meccano...I'm thinking earrings next, or spraying the plates bright colours for a necklace with a pop of colour. Some of the larger, longer plates could even be manipulated and bent to form bracelets.