Interior non camping Dash tidy bracket
Here is a scan of a bracket I made for mounting a dash tidy, it has been drawn around on a sheet of A4 (1:1) so print this out and use it as a template for yours (cut round the internal edge.) I used three, with right angle metal brakets to hold it to the dash. I used a sheet accross the top for the shelf, all in (10mm MDF). Cut holes for your favourite insulated mugs, and cover with some non slip material (halfords do some for parcel shelves). Also creates a nice hidey hole underneath which could be used for extra storage if hinged fronts are added. this sticks out a few inches back from the dash to maximise the shelf space (but still allows for a cab hammock resting on the doors), you may whish to pad the leading edge of it in case of an accident, maybe with some pipe insulation foam. Jobs a goodun.
Edit: Tip from CovKid.
I found that two black, sturdy seed trees from the famous pound shops (it was 4 for a pound I think), using double-sided adhesive pads and stuck to the unused portion of the dash, holds most of the cluttter I had up front and doesn't need any drilling. Its another option anyway. Agreed its not perfectly level but had nothing fall out so far.
For cup holders you could use any of the proprietry ones available for about £7 if you needed that facility.