Hi guys,

​I need advice from experienced woodworkers regarding a DIY freestanding bench/riser I am building:

\- ​Material: High-density particle board kitchen countertop (approx. 28-30mm / \~1.1 inches thick). 

\- ​Dimensions: Top plate is around 130 cm (\~51 inches) long. Legs are made of the same countertop material (60 cm wide).

​- Load: A cabinet weighing around 50–60 kg (\~110-130 lbs) filled with cleaning supplies and liquids, positioned on one side. In the future, I might add a second smaller cabinet on the other side to balance the load.  (I added around 10kg + just in case)

\- ​CRITICAL CONSTRAINT: I cannot drill into the wall because of tiles. The structure must be 100% self-supporting and rock-solid, as my cats would use the litter boxes underneath. Safety is my #1 priority.  

​My Questions:

​Will a 28-30mm countertop sag over a 130cm span under this load? Do I need a middle support leg or an additional frame unter the plate?

​Since I can't anchor it to the wall, how do I best prevent lateral racking / shearing?  

​Are metal corner brackets under the top enough, or do I need a rear stretcher / apron / backboard to lock the legs in place? What hardware works best with particle board to prevent screws from pulling out? 

As a machinist, I know there are engineering/machinery handbook formulas for material strength and stability. Is there an equivalent for woodworking and furniture making?

​Thanks in advance for your expertise!

Advice for a novice