Sure you can always create your own layout using Keyboard Layout Editor Tool bundled with Avro...but there are other free options as well.
For Die-Hard fans of Bijoy-like keyboard layout:
Although Avro is not including UniBijoy layout since the past two(?) versions due to conflict with MJ of Bijoy, you can still download the following from the web/net which are virtually almost identical to the Bijoy layout, just Google them:
UniBijoy itself, CloneJoy, Bijoy in Avro, et al.