Families, schools and local companies will get stuck into building a huge chain of crazy contraptions that trigger one another around the room and across the stage at the Guildhall in Cambridge.
As well as building your section of the chain, visitors can engage with exhibits from the Cambridge Science Centre. There are even prizes for some of the best entries from schools, company teams, and the public.
Chain Reaction is open from 11am with the launch taking place at 4pm.
Those wanting to take part will need a Building Pass, priced at £25. This will allow you and up to 5 others to build a section of the chain, access to building materials and help with your design from staff on-hand. No other entry is permitted except for those taking part in building the Chain Reaction.
You can build some or all of your part of the chain at home before the event and bring along what you have made for final tweaking on the day. Have a read of the guidelines here.
Tickets are on sale now.