Sorry to rain on your parade, however it would probably be easier / cheaper for someone to do similar to what i have done wth my monty bars. get some dowel ( i used 20mm or something similar), cut it to length (i used two inches), then hammer it into the end o the bar up until half way in. then get some masking tape to make up the difference between the bar and the dowel. Works a treat, and you have bar bungs and wider bars as one