Not sure on the use of chia seeds, but if the question is grinding, a coffee grinder works well.  Can usually find them in a thrift store.

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Rose D in Hawaii 2022

case History:  https://ecir.groups.io/g/CaseHistory/files/Rose%20and%20Luluka
Photos:  https://ecir.groups.io/g/CaseHistory/album?id=277362