Spiral staircase removal and replacement

Ive looked everywhere. I thought this was a diy forum but.... Anyway. I have quite a bit of scrap wood and a chipper (and quite a few more tools) and looked at osb and thought " i have alot of that laying around. Shouldnt be that hard to press and glue it together. I looked up the types of glue and resin that are used and typical proportions. Not sure about the stregth axis it has but i understand orientation of wood pieces. So would i beable to press it out and thats it? Is there something im not aware of? Why is noone else doing this? Please awnser back. As i said ive looked all over and can get a concise answer.

I want to install wainscoting from one wall perpendicular to another wall. One wall has the standard 5 1/4 inch baseboard trim where the perpendicular wall has 8 1/4 inch baseboard heater trim. We are trying to decide what looks best. Do we make the boxes of wainscoting the same size height from wall to wall leaving the bottom gap considerably smaller over the heater, or do we shrink the box height size over the heater to maintain the same gap from wall to wall? Example, the gap below the boxes over the regular trim will be 3 1/2 inches where as if we were to maintain that same gap over the heaters the box size would decrease in height size. However if we were to maintain the box size from wall-to-wall the gap from the bottom of the boxes to the baseboard heaters would be approximately 1/4 to 1/2 inch. I hope that makes sense and I appreciate your input. Something tells me it’s going to be whenever we like looks better? Again thank you.