What should the dimensions of an imported mesh be?

Hey guys, I have a designer making shapes for me to import into my babylon scene, and he is making the shapes of type wavefront object (.obj files). Once he sent me the first shape to import and test out, the shape was too large. In order to place it on the ground properly and to be almost of the same size of a box of size 0.5 I had to scale the shape like this " root.scaling = new BABYLON.Vector3(0.0006, 0.0006, 0.0006);". This just makes it way more complicated for a user to edit the shape the way the user wants. The main question here is what dimensions could I give the designer in order for him to create a shape of the same dimensions of a box of size 0.5 in babylon? I dont want to keep testing out different values in order to resize the imported shape in a way that it fits with other 0.5 sized babylon shapes.

Typically the unit of measurements is in meters. Especially in VR you will find that will make scaling easier. So, when you say 0.5 then hopefully that is 50cm for your designer.