I have my laptop computer camera covered with tape and the selfie camera on my phone covered with tape. I leave the outward facing camera uncovered (so I can snap a quick photo) and always set my phone down with that camera down. I usually use the speaker phone feature if I'm talking on the phone, so I'm not irradiating my brain. That also allows me to keep the camera pointing down onto a table, desk, or other hard surface. This seems to be the best compromise between convenience and blocking cameras.