This is how to make an adapter cable for your Sony RX100 M1, M2 or M3 camera so that it can use an external intervalometer to make time lapse shots. This might work with other similar cameras that use Sony’s special “multi-terminal” USB connector which allows for the connection of a wired remote control such as the RM-VPR1 (although the RM-VPR1 remote is NOT required to make this cable). But note that for some inexplicable reason this will NOT work with the Sony RX10 camera.
The intervalometer used is a cheap Chinese model of the sort you can easily find by searching eBay for “Pentax Intervalometer“.
The adapter cable used is a Sony VMC-AVM1, which is normally used to provide a LANC connection to a Sony camera. It’s available from about $15 on eBay to around $20 through official retailers. It’s a lot cheaper to buy this adapter cable than to cannibalize the cable of a much more expensive RM-VPR1 remote.