I know you can multiply CFrame.lookVector with a number to a part's position in order to make a part appear in front or behind another part (in this case the player's torso.) But, I'm wondering how you move it's position to the sides or the player.
Here's a script you can edit if you need to:
local Torso = game:GetService("Players").LocalPlayer.Character:WaitForChild("UpperTorso")
local part = Instance.new("Part")
part.Position =

2 comments
CFrame.rightVector? Also replace "UpperTorso" with "HumanoidRootPart"
I used UpperTorso because the part is going to be welded to the player, and is supposed to move with the uppertorso.