Wood is all 19mm MDF except the back panel and the horizontal boards are wedged between the sides and held by 2 screws on each side. I want to reduce the chance of the shelves sagging over time.
How much weight should the current unimproved construction be able to hold?
I intend on storing all my power tools inside here, so no more than 10kg per shelf. In order to prevent the boards from bending over time the current plan is to stabilize them from below.
How would you stiffen the shelves without wasting too much space?
I know this construction isn't the best but the shelf won't be used for storing Olympic plates. Just a few screwdrivers and grinders etc.
On request I got my SLR + tripod and made some shots. The place is still in a bit of a mess though: