I would start with filling the product with potting compound, which has been a standard process in tamper-proofing hardware for a long time. Keep in mind the whole value proposition of a hardware wallet is security.

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lxgr an hour ago | parent [-]

Are you sure that that's safe to do with a device containing a lithium ion battery? These usually have emergency gas valves to prevent explosion.

	▲	tristor an hour ago \| parent [-]
		Yes, it's safe to do with lithium ion batteries as long as you use the right potting compound (potting compound isn't just one thing). There are compound specifically designed for battery encapsulation that assist with thermal management and preventing ruptures. As the person you're replying to has already stated, using potting compound to fill in cavities and discourage tampering on electronics is a standard practice. Depending on your design requirements you can also use different battery chemistries or cell constructions to minimize the need for mechanical venting.