``` c#
TSM.UI.Picker picker = new TSM.UI.Picker();

try
{
            ModelObjectEnumerator boltGroupEnumerator = picker.PickObjects(TSM.UI.Picker.PickObjectsEnum.PICK_N_BOLTGROUPS, "Please pick the bolt groups to investigate their tolerances.");                // unfortunately you have to select all the groups of bolts individually
}
catch (Exception ex)
{
            MessageBox.Show(ex.Message);
}

////    **Gripe Alert – please skip if you don’t like hearing folks gripe:**
//// But quelle surprise, yet again the Tekla Open API designers have outdone themselves. If you want to select groups of bolts (plural),
//// you can’t use a window or crossing selection – you have to individually and painstakingly manually select every single bolt
//// that you see *individually*. Brilliant, that’s why we have a picker that can select multiple objects – only for it to work
//// on an individual basis. Perhaps in Tekla Version 23 the Tekla Open API team can force developers to resort to using punch cards?
```