Apart from what has been said, I would talk a lot with the guy who's going to use them. He's the one who knows best its limitations and small little details that we would miss.
For instance, apart from lowering the height of the pieces, depending on its use he may need to go under them with the wheelchair, maybe there is room for his legs but not for the armrests of the chair.
Depth is another dimension to consider. Opening and closing doors and drawers is not as easy on a wheelchair that standing. When we open a cabinet we either strech our arm or we retreat a bit, those simple movements are not that inmediate on a wheel chair.
Designing for handicapped people is a great challenge and unfortunately not addressed and solved properly most of the times.
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I also dream of a shop with north light where my hands can be busy, my soul rest and my mind wander...