mesh.clone

mesh.clone brings a mesh object into being: it is how the rest of the script comes to have one. It takes id and newId.

mesh.clone(id, newId)

function start() {  mesh.createBox('box', { size: 1 });  mesh.clone('box', 'copy');}

mesh.createBox is there to give the call something to act on; mesh.clone is the line that matters. The code sits in start(), which the engine calls once, when the entity spawns.