As we have written previously, boards for lining out are available in a variety of finishes and thicknesses. The most obvious and commonly seen linings are made from sheet materials with a decorative surface finish such as Oak or Ash. If you are planning on a tongue and groove final finish then standard unfinished ply sheeting can be used as a backing. 6mm unfinished sheet is more than adequate for backing boards and 9mm veneered or laminated sheet is commonly used for standard lining out.
For cutting multiple power point access and light switch apertures it is worth making a template from timber sheet that can be used time over to ensure the apertures are consistent.
Cutting apertures is best done with a vibrating multi-tool cutter as jig saws can be aggressive and awkward to use on vertical surfaces. The multi tool cutter also allows greater control thus avoiding the possibility of slicing through electrical cables.