I also put the powder in these by hand - XPRS Nutra Size 0 Empty Capsules... https://www.amazon.com/dp/B07X6KT8LC?ref=ppx_pop_mob_ap_share

I got a bunch on Amazon that I use to add plant food to the capsule. Then I can bury the capsule into the substrate of my aquarium to feed my plants. Here’s an example

https://www.amazon.com/Capsules-Express-Clear-Empty-Vegan/dp/B07X6KT8LC/ref=mp_s_a_1_1_sspa?crid=10O03KIXV7ID5&keywords=gel+capsules+empty&qid=1645832706&sprefix=gel+cap%2Caps%2C151&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUFSNVdFSU05WUhRRFomZW5jcnlwdGVkSWQ9QTA5MzI3OTczTURVRU9HS1FRR0FFJmVuY3J5cHRlZEFkSWQ9QTA0OTc4MDBLQzY3QTkyU0ZLSFUmd2lkZ2V0TmFtZT1zcF9waG9uZV9zZWFyY2hfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==