Unsure the best way to apply transforms to geometry

[SoggyBottomBoy]

I am after some help as I am both not overly familiar with the library nor 3D modelling. Basically, I am writing a light wrapper around the HelixToolkit for creating 3D charts specific to my use case. On thing that I want to do is scale the axes based on the bounding box of the chart series added. Because this is a light wrapper I use the HelixToolkit types for defining my chart (i.e. the consumer is expected to add a series as a GeometryModel3D).

What I want to do is combine the bounding box for each series, create a transform to scale each axis (i.e. to end up with a cube), and then apply this transform to each series. I have done the first part (calculating the transform), now do I need to write the code for apply transforms to the various derived types of GeometryModel3D or if there are already helper methods to do this.

Any help much appreciated.