The DJI Ryze Tello is a great little quadcopter, and I used my 3D Printer to make a case, then later on I bought one.
3D Printed DJI Ryze Tello Carry Case
The DJI Ryze Tello is a very popular Quadcopter, so Thingiverse is the place to go if you have access to a 3D Printer. This is a Dji Tello diy accessory that you can print directly from your own 3D Printer I got my stl files for my DJI Tello Accessory Case from thingiverse. Thingiverse have many different Tello accessories for your to 3D print, and are constantly updating them.
When I purchased the Carry Case above for my DJI Ryze Tello mini drone (over 6 months ago), there wasn't a lot of Tello accessory cases available to choose from. Now I think there are better Tello case choices available, if you do a bit of an online search you will find them. I have included some links below, I personally think the AliExpress case is the best one I've seen so far.