The Chatterbox is a DIY smart speaker that even children can build. The device has a chipboard case and is built around a Raspberry Pi 3B. The speaker can be taught new commands using the Chatterbox app too. The Chatterbox is currently available for US$119 on Kickstarter and ships worldwide in December.
https://www.notebookcheck.net/The-Chatterbox-a-Raspberry-Pi-smart-speaker-that-you-can-build-and-teach-yourself.421446.0.html