Simply, a question: in the previous version of Blender you were finding it -the ‘symmetrize mesh command’- in the scroll appearing by pressing the space bar. Now, in 2.8, where do we find it? I made a search in the Net but in vain. Where, in the 2.8, are all those commands which were appearing through the use of the space bar in the previous version?
You should try to search in Blender’s menus.
Symmetrize is under Mesh menu in Edit mode.
It is also under Dyntopo panel as in 2.79.
In default keymap, search shortcut have been changed from spacebar to F3.
You can re-use 2.7x keymap by simply setting the preset under Keymap section of User Preferences.
There is also a quick way to precise spacebar’s use : to play animation, to precise active tool or to search.
Thanks a lot Zeauro, will look at it!
You can also use the mirror modifier with bisect option checked! NIce