Some several weeks ago now I was in my local R/C Hobby store buying other things when I noticed a new line on the peg board. A pack of pre cut, self adhesive weights. Meant initially for trimming aero models, I could see their application straight away. The weights are made up like little squares of chocolate and can be 'peeled' off and fixed in a jiffy. Once you have reached optimum ballast it is a simple task to turn them over and superglue them in place!!