If you want to try here’s how –

Take 6 – 8 inch softwood cuttings May/June.
Wound and treat with 1% – 2% IBA.
Stick in pearlite/sand mix and maintain mist until Fall dormancy.
Overwinter in cold frame.
Up pot in early spring.
20% to 80% success rate depending on cultivar and age of donor tree.

Probably not worth it unless you’re doing lots of cuttings.

Air layering will (usually) work if you are looking at a specific part of a tree to work with.

If you just want some small maples to work with, find a supplier of liner stock – these small trees are inexpensive and are young enough to start bonsai culture right from the start. Here’s one that will sell to the public –
http://www.sunsetgrowers.com/japanesemaple.php

References :
Bonsai grower – nurseryman