To cast music to nearby devices on your WiFi network, just tap the Chromecast button on the bottom left of a playing/queue screen or the top right of a track/album page to connect.
Then start casting your Bandcamp collection to any nearby Chromecast-enabled device.
Don’t see the cast button?
Head over to your collection and click the gear icon on the right to see your settings. Scroll down to the "Chromecast" section and make sure you've followed the prompts to enable Local Network Access.
Still no luck?
Go to your device settings to make sure you're on the same wireless network as the device you’re casting to. If your mobile device doesn’t automatically find your devices, or there is no Chromecast button, you may need to download the Google Home app to set up your streaming devices.
This link should help with that.
And for those of you keeping track, when on WiFi, the stream will be MP3 V0.