How do you project where the building is going?

Hi, so i want to make a Building System sort of like Bedwars. I've got the basics done, so far but I need help on when the mouse doesn't have a tareget and it projects where your mouse direction is. If its going on the left side or the right side it all depends on where your mouse is. Heres my code:

local NewCast = workspace:Raycast( workspace.CurrentCamera.CFrame.Position, Mouse.Hit.LookVector * 100 )
    if NewCast and NewCast.Instance.Name == "Block" then 
        Selection.Adornee = NewCast.Instance 
    else 
-- the part down here is what i need help with
    end
end)

Thanks for any help :D!