bamboo palanquin
箯 refers specifically to a bamboo palanquin, a type of sedan chair or litter made from bamboo.
箯 combines 竹 (bamboo) with 便, which likely contributes a phonetic element. The character specifically denotes a bamboo conveyance.
The bamboo radical 竹 sits above 便, suggesting a convenient bamboo carrier: a bamboo palanquin.
For ヘン, imagine a hen riding in a bamboo palanquin: hen -> ヘン, and the hen is carried comfortably in the bamboo litter.