Anyone used one of these kits off ebay or would i be wasting my time and money? Any tips on prep etc

 

have a look for the machine they use to do model railway grass, better suited to the job

 

Ok for small bits and bobs and a bit messy

For a whole dash I would be looking for a professional to do it, costs about £150 and is applied using electostatic giving a nice even finish a bit like powder coating