Forest People tents [1] are semi-permeable, clear bubble tents made from insect fluids [2]. What insects are milked for the fluids to create the tents or how they are manufactured is unknown. Water Turbines are used with tents to filter the Miasma out and keep a safe atmosphere, even in the most dangerous and poisonous parts of the Toxic Jungle.
Since the walls are semi-permiable, Ketcha freaks out when she accidentally puts her arm through the tent wall [3] but the tent does not collapse, nor is dangerous miasma let into the tent. Entering and exiting the tent is done by simply walking through the wall bubble. It seals around and behind the person transversing the insect fluid barrier.
By the end of their stay with the Forest People, Ketcha and the rest are comfortable in the tents.
Reference[]
a See Page Conversions Between Editions to convert Deluxe Edition volume 1 (DE1) to other editions