I found a nice silicone cover for the microbit (a Kittenbot). Then I tried to stick it onto the smooth back of a communication device...
I found some sticky back Velcro with extra sticky glue that seems to do the trick. The silicone is a hard thing to get anything to stick well to.
On my 'to do' list is to use my new and shiny 3D printer to make a case for the microbit that clips easily onto the back of a communication device. This would be a neater solution than sticking bits of Velcro on.
On t'other hand (as we say Up North), the whole idea of using a microbit is to make it easy for anybody to implement this project. Sticky back Velcro works and is easy to get hold of. Not so many people have access to a 3D printer.
I admit it, I'm looking for an excuse to use the 3D printer for something original, after cranking out face shield clips for local care homes. Which made me get to grips with the basics of how to set up and use the machine.