Next week I am shooting some firework displays and I want to be able to have two cameras on a tripod one on a wide & another on a not so wide, however all of the remotes that I own don’t support keeping the shutter open in “Bulb” mode so I am going to make a work around, all in it will probably cost a ‘tenner’ but it will enable me to synch the two cameras. Some of the parts have arrived from RS Components, just waiting on a couple of 3.5mm sockets to finish it.
[Update] All finished and working as it should. I could have installed an LED and an On/Off switch but that would have added some additional bulk & weight.

Finished Remote Trigger