I have an open but mostly full 2.5kg bag of "Kontrol Krystals" calcium chloride crystals to put in refillable dehumidifiers. There's about 2.25kg left.
A family member gave them to me, but we have no use for them. They're sold for use in refillable plastic dehumidifiers, but I imagine you could make one yourself if you wanted.
If you're interested, please let me know when you'd be able to collect.
Calcium chloride dehumidifing crystals (Enfield EN2)
This offer has been gifted to someone and is no longer available.