Do the designs of the larger units lend themselves to being cut down? That would likely be a costly hack job at the price of these unless a damaged one could found in the Returns Room at Ikea.
I have learned so much on these forums, and can rarely contribute any help because 99% of the people here can sweep me under the rug with their knowledge. I believe in ‘pay it forward’ so here is my contribution :
I took a blind down and disassembled it to get measurements.
That answers the question of how these would slip onto the motor unit if cut right down to nothing but the end bracket.
This documentation will be helpful for other I'm sure. These can be used for "more than just a blind" when cut down to that size. As you pointed out with Ebay , they are available for cheaper if one really just wanted "the guts" more than "the blind".