This is the second iteration of my more powerful stepper driven roller blind. You may find the original here, which includes more photos of the original clutch that came with the blind. https://www.thingiverse.com/thing:4771130

The blinds I have (https://www.selectblindscanada.ca/roller-shades/value-vinyl-blackout-roller-shades.html) are large double thick, and well built with 1/8x1" aluminium as the weight. They also are on very large diameter rollers so lots of power is needed. The vinyl and weight weigh around 2 kilos....
The design uses a clutch system that will hold the curtain when the motor is off (don't want to start a fire...).

I used a bearing as a idler gear.

I find it powerful enough with a 2a stepper but it's quite noisy so I am moving over to a belt driven system. I will add a Remix of this one once I have a better design.

I have included two 'frames' that connect the the metal bracket that attach to the wall, one is a 90' which is for me as it is ceiling mounted. If you wanted to adapt this design, you should remix the frame to either be mounted inside the window frame or directly to the wall or to use your existing wall bracket. Look at my previous design for better photos.

Some of the things I used and referenced as I am quite new to stepper motors:
I am using a stepper driver
drv8825
https://www.makerguides.com/drv8825-stepper-motor-driver-arduino-tutorial/

arduino
accelstepper
https://how2electronics.com/control-stepper-motor-with-drv8825-driver-arduino/

How to control a stepper motor with DRV8825 driver and Arduino
https://www.makerguides.com/drv8825-stepper-motor-driver-arduino-tutorial/

Please check out my next design iteration that uses belts, and silent stepper motor drivers.