While the UI isn't set up for it atm, the database already handles the case of more than 49 unique parts. My idea was to have several of these grids stacked on top of each other in a shelf, so you'd be able to flip through the layers, each containing up to 49 parts.

For my purposes, the bins are small enough that I'm fine with only keeping a single part in each bin. The problem is however related to something I was considering, namely multi-square bins for bigger parts. I decided against implementing it simply to reduce the scope for now, but it is for sure possible.

If I were to place multiple parts in a single square, I'd probably subdivide the bin and keep related parts in each sub-bin. Perhaps resistors in a series of Ohms or resistors with the same resistance but different sizes.