Is there a way to mirror an object without using the mirror modifer? Is there a way to mirror an object without using the mirror modifier?

I have a left foot that I want to make into a right foot. I use the mirror modifier and it uses a crooked bounding box and completely ruins my foot. Even when I re-align the crooked foot, it is causing issues in the platform I'm exporting it to. So I'm wondering if there's some way I could duplicate the left foot and somehow flip it so that it "mirrors" the other foot.



Please ignore the flat feet there, I need them for when I transfer weights.



I duplicate the foot so that I don't mess up all the work I've ALREADY done over and over, and move it to another scene. This is the foot I want to mirror so that I may create a perfect opposite for the other leg. Something goes wonky when I do that. It mirrors with a bounding box even when I use empty. This causes me to have to re-align the mirrored foot. Something else is happening too because when I rez the mirrored foot alone in Second Life, it really acts weird. The original foot can be rezzed in world with no problems. This makes me feel like it's the mirror modifier that's causing all my troubles but I'm really not sure.
Here is the crooked mirrored image:


Here is the bounding box, where it shows it's crooked:
You can do this destructively by scaling around the 3D Cursor. Place the 3D Cursor at the center you want to mirror across. Next, choose the axis that you want. Hit ., to set the Pivot Point to the 3D Cursor. Finally scale it by negative 1 along the desired axis.

S then X, Y or Z then -1