There is no way to mirror all features from body but find herewith 2 methods that can help
1st solution if you need 2 different parts:
file save as
associative copy
then you can edit the original features
2nd solution if you need 2 solids in the same part:
Assuming that your first feature is based on a datum csys
create a new datum csys
copy your first feature
then paste it on the new datum csys
associative mirror copy the new solid
then you can edit the pasted features
Didier