Wristband for Mi Band 4

The Mi Band 4 is really a great smartband that does its job well, but two things have always bugged me about it: How short-lived the stock wristband is (same goes for similar replacements), and how often the band accidentally snapped open. So, I tried my hand at designing a printable wristband of my own!

This replacement band can be printed from TPU with a Shore hardness of 95A or higher. I used Polymaker PolyFlex TPU95, which worked pretty well, even on my bowden printer (Prusa MINI+), and gave me a result that has just the right amount of flexibility.

The “normal” version of the band is suitable for a wrist circumference between 138 and 176 mm; the “XL” version goes up to 192 mm.

To assemble everything, you need two 15 mm pieces of 1 mm spring steel wire (or pieces of carbon rod of the same size), and the pin from the stock wristband.

Print settings (Cura):

Nozzle Size: 0.4 mm
Layer Height: 0.15 mm
Outer Wall Inset: 0.1 mm (helps getting the overhanging parts printed)
Infill density: 20%
Speed: 20-30 mm/s
Combing Mode: Not in Skin
Enable Coasting: Yes
Supports: Yes

Material and settings:

Material: Polymaker PolyFlex TPU95
Print Temperature: 228 °C
Build Plate: Textured steel sheet
Build Plate Temperature: 55 °C
Flow: 115%
Fan: 60-80%