Front Sprocket Freewheel

I am sure some members have found commercial solutions to a front sprocket freewheel on a 3 piece crank, but I was unable to find a long enough shaft for the right hand side. Sick Bike Parts sells a long spindle on left hand side, but that was not what I was looking for. I have posted a video on Youtube that chronicles my experience. I hope it may help others. https://youtu.be/fX-_9WoTshg
The $200 bicycle project can be seen at https://youtu.be/UthRxU0_Es4

That is pretty awesome.

Bicycle freewheel cranks are typical on Trial bikes. Many different can be found, but none cheap.

Other solutions had been explored for a while on ES, enough to find what you need with a search. Here is the first result I ´ve got:
https://endless-sphere.com/forums/viewtopic.php?f=28&t=7641

I have snapped off square taper spindles a couple of times, once at the cost of several teeth. And I'm not the only one; I know some high mileage riders less than half my size who've broken more of them than I have.

This is to give context when I assert than using an externally threaded shaft as a bottom bracket spindle is a reeeally bad idea. You've reverse engineered a thing that only works when it's made from fully hardened steel--- and only works most of the time, not all the time. You made it longer, for more leverage with which to break it, and you made it from a softer, weaker material. And it's covered with stress-concentrating notches. It's just itching for an opportunity to let you down.

I applaud your creative thinking here, but at the same time I think you should never use the thing on a ridable bike.

ISIS standard is the best thing that happened to bike cranks in a century. I would not return to square taper unless it was a vintage restoration.

Large spindle diameter is a welcome development; however, ISIS cranks particularly have a tendency to loosen and become damaged much more often than most other types of spindle interface. It's the right idea, but a problematic implementation.

At least it's much better than Octalink V1 and V2.

Lighter and stronger at once, we can’t ask them to last forever.
However, some proper implementation of ISIS is available in MTB , and those can stand hitting rocks and curbs pretty good.

I believe some square taper are not that bad, if you are willing to pay 1000$ a forged Titanium BMX crank.