Most of us have our HP41c in the original vinyl case. For some reason, this case was made big enough so that the calculator could be stored together with the card reader. This was done under the assumption that a significant part of the users would buy the card reader - which may have happened at the very beginning but definitely not later on. The serial numbers of the card readers that I receive are typically from before 1982 - so that may be the reason. Anyway, all cases were long, except from some cases like the one on the right that may have been made for another calculator.
For those users that had not bought the card reader, HP included a yellow sponge to pad the calculator into the long case, so that it didn't "dance" inside the case. These sponges are now quite old, and have taken a "greenish" color. Many of them have been contaminated with the dust coming from the degradation of the internal lining, and some of them are lost. We have commissioned a sponge from a foam producer. It is white but nevertheless the right size and texture. Not worth an order (just 1€!) but worthy to complete the one you already prepared!