Ikea LACK floating shelf support

Right…. I have (inherited) a couple of the Ikea LACK floating shelves and they sag if the feather on them is too heavy. So, I wanted to come up with a quick solution to add some support and use some 3M command strips to hold it in place. I had a play around in Fusion and came up with three random alternatives. So, I used one, but have uploaded all three - just in case someone else fancies trying the less conventional versions. Due to the way in which the cantilever design is implemented on the shelf, it is viable to fit only a single support in the centre. This is what I've done. Just attach four large Command Strips to the vertical face.