Hi, i recently had some cranks old alloy cranks which had the old anodize finsh very sctrached, i wished to get rid of them and so took them to the metal work apartment of my college and was able to leave them looking pristine and sctratchless, i had to use serious industrial machinery for this, i think your best bet is serious equipment, although be carefull because its very easy to remove a couple of mm's from the circumference of your seatpost and then your shiny new seatpost is ruined!
Hi, i recently had some cranks old alloy cranks which had the old anodize finsh very sctrached, i wished to get rid of them and so took them to the metal work apartment of my college and was able to leave them looking pristine and sctratchless, i had to use serious industrial machinery for this, i think your best bet is serious equipment, although be carefull because its very easy to remove a couple of mm's from the circumference of your seatpost and then your shiny new seatpost is ruined!
Good luck