Here is the prototype of my low-humidity container, which is supposed to keep the Sylphyo protected and reasonably dry. Seems to work, the long-term test is still pending.
The case is from Ebay, it's built by a hobby carpenter for displaying model cars and trains, and is originally intended for horizontal use. I just treated the raw plywood with linseed oil varnish.
At both ends the manufacturer provides acrylic glass plates, additionally I inserted two small wooden boards with holes. I put the Sylphyo only dry in, nevertheless at the lower board a usual kitchen sponge cloth lies, in order to catch possible dripping from the instrument. The small faces of the acrylic compartments and wooden boards have gaskets that rub lightly against the large acrylic faceplate. In fact, the gaskets are slotted sheats of audio cables.
To put the Sylphyo in or take it out, I slide the front panel up. The mouthpiece has its holder right above the Sylphyo’s body to remind me not to put it in with the mouthpiece on. The USB cable goes into the box at the back.
The construction is pretty tight, though not airtight in the technical sense. I trust the microclimate. If it works, I will probably screw the case to the wall. I have to add that I don't live in a very humid climate (Austria, Central Europe). With wooden instruments, for example, we rather have problems not letting them dry out from room heating over the cold season.
I hope the Sylphyo will feel comfortable in its new home, until now it had to hang in a cloth bag on a shelf.
Wooden box with acrylic glass panes from Ebay: €70 ($76)
1 kg (2.2 lb) silica gel from Amazon: €20 ($22)
Two nice bowls for the desiccant from the kitchen supply store: €8 ($9)
The other material like small plywood boards, some screws and linseed oil varnish I had at home.