There are 2 methods to mirror a model in Poser. Here's one of the methods: 1. Load the model (import the obj geometry, or load from a prop library). 2. Use the one-dimensional scale dials: xScale for a left-right mirror, yScale for an up-down mirror, zScale for a front-back mirror. 3. To mirror left-right, set xScale to 50%. 4. Export the model as Wavefront obj. Disable (uncheck) all export options. 5. Reset xScale to 100%. 6. Create a new morph target (MT) from the exported obj (use menu "Object > Load Morph Target", and locate the exported obj). 7. The new MT dial performs the xScale deformation. Set the MT dial to 4, to create the mirrored object shape. (MT value 1 = 50% scale, 2 = 0% scale, 3 = mirrored 50% scale, and 4 = mirrored 100% scale). 8. Open the group editor. Click "New Group" and "Add All", to include the entire model into a new group. The mirrored model has "reversed normals" (the surface is inside-out). To normalize the surface, click "Reverse Group Normals". 9. Click "Create New Prop" to create the mirrored model.