About UDynamicMeshComponent, UDynamicMesh and FDynamicMesh3.

UDynamicMeshComponent

UDynamicMeshComponent renders a UDynamicMesh. See UDynamicMeshComponent::SetDynamicMesh.

UDynamicMesh

An UDynamicMesh is a wrapper for a FDynamicMesh3. See UDynamicMesh::SetMesh. See UDynamicMesh::ResetToCube for an example on how you can use UDynamicMesh::EditMeshInternal to append shapes and do other actions.

FMeshShapeGenerator

This and its subclasses can be used to generate a FDynamicMesh3.

See the FDynamicMesh3::FDynamicMesh3(const FMeshShapeGenerator* Generator) constructor. This allows to do this like:

FMinimalBoxMeshGenerator BoxGen;
BoxGen.Box = UE::Geometry::FOrientedBox3d(FVector3d::Zero(), 50.0 * FVector3d::One());
FDynamicMesh3 EditMesh = FDynamicMesh3(&BoxGen.Generate());