How to mirror or flip duplicates in edit mode? I'm currently trying to create a duplicate of the character's shoe with the shift + d method but I'd really like to know if I can flip/mirror the vertices selected so it'd look like I have a left shoe, not just two right shoes.

Normally what I would do is duplicate the model, then delete everything I need however for some reason this stops the shoe from following the rest of the model(and that's after I've rigged the new shoe, weight painted and everything) so I'd like to know if there's a way to just flip/mirror only the vertices I have selected in edit mode? Similar to how you van horizontally flip an image in Microsoft paint.

Here's a basic image of what I'm trying to do:



I'm sure there must be a way to do something similar in blender, it seems like something that would be part of the program, any advice would be greatly appreciated :)
There is an easy way to do that. Set the 3D cursor in the middle between leggs (it would be probably a characters pivot point) then, set pivot point for transforms to 3D cursor and Shift+D to duplicate, then Enter or right click, then CTRL+M and choose axis on which you want to mirror the shoe by pressing X or Y. After that you should have mirrored shoe on the other side of the cursor.Like this: