I use a bag made for Jeep door tops. Surprising how much cheaper they are.
Then again, maybe it shouldn't be surprising. But Rover door tops fit in these.
https://www.amazon.com/gp/product/B...4df-15aac5223b10&pf_rd_r=5XQ08F5AYT0VRT45NV8E
They are big enough to accommodate a Series 1 door top also.