Walkr has 10 different models of DFR:

• 5 regular DFR models that may randomly appear
• 5 special DFR models that can be built by obtaining their blueprints (1 blueprint per DFR)

The names of the 10 DFR models are as follows:

• 5 regular DFR models: Food Generator, Ultrasound Juicer, Lightspeed Toaster, Electromagnetic Rice Cooker, Space Coffee Machine
• 5 special DFR models: Toaster Oven, Automatic Coffee Machine, Sushi Chef, Automatic BBQ, Space Ice Cream

If you'd like to ensure you get all 10 DFRs, you can complete 10 different DFR factory travel epics to get 10 DFR blueprints. After that you'll be free to select whichever model you'd like to use! (DFR blueprints can also be used to build regular DFRs.)