Allen + Roth Blinds - Cordless Cellular Shade Blind Handle Tab

Flat sided - to print on its side for layering strength.

The number on the bottom of the original pull tab - P15BH2

I included a 5mm thick test part so you can check the fit before final printing. I'm not sure if there are more than one bottom rail profiles. 

According to users this also works with Home Depot's Perfect Lift blinds. I have not tried it for that application.