Careful what you use to glue the coils to the surface if you want to get them out later. Acetone, CA debonder and electric motor cleaner are only three solvents that I know will remove the insulation enamel from the coil wire and ruin it. CA debonder caused a coil to delaminate and come un-wound. The winds of that coil may have been bonded with CA.

I started using only Elmers School Glue to attach coils. A little water will allow it to be removed from the airframe undamaged.