In case anybody is interested ! Thanks @nickmBY “Backing Paper” is ‘baking paper’ or ‘greaseproof paper’ or perhaps ‘baking parchment’ very high temp and bugger all sticks to it 
Yes, baking. Backing is not what I intended to write. I guess my brain was already at the cacke (that I didn’t have). 
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Yeah well put. This idea is quickly falling victim to the over-engineered trap. Still makes for an interesting project, but the generic-tool and specific-workflow approach is hard to beat. By that I mean just doing the components by order of their height makes a sheet of foam a pretty effective tool!
FWIW, I’ve been persevering because the knowledge-generating benefits of experimentation are in strong effect. I have lots of advice on CAD forums about trying permutations of joins and cuts and intersects, but I’m hitting huge headwinds trying to work with the 3D models. A slip of the mouse in Fusion 360 or FreeCAD can send them into unpredictable hour long lock-ups consuming 10’s of GBs of RAM, so the test/review cycle is pretty excruciating.
I did get one successful cut done:
But it’s teetering on the edge of an unworkable model, so I haven’t been able to add the tolerances and detail I need to make it practical. My goal always seems just out of reach!
I’m now trying pre-work on the cutting tool instead, but am mostly just finding more delightful ways the CAD packages can crash. Some experimental debris along the way:
I typically just use open-cell foam for this. Typically two or three passes. First the resistors and diodes, next larger parts and finally the tallest.
Well I definitely like and appreciate the idea. It makes me think of all the things I have way over engineered and over thought for sure. It;s good to get these ideas out on forums like this, it can always work for someone in a special case or spark other ideas for sure.
A little off the subject… At one time, there was a lot of th editing now dominated by smd and the output is put on the press or machine… Many years ago, working at the factory, we had a pierced hand tool for forming the outputs of capacitors and resistors… There were all sorts of patterns for bending at an angle… I wanted to buy but I can’t find anything similar… Maybe who came across such a thing?
I’ve had one of these gizmos for several decades, very handy for bending resistor, diode, etc. leads. https://www.sparkfun.com/products/13114 I’m kind of surprised to see them still available.
Also common back in the day was a spring-loaded cutter that would “clinch” the leads and cut them off which held the component in place until it could be soldered. My Google-fu failed to turn up an example.
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Thank you!.. I didn’t manage to find even this))
That’s pricey for a piece of plastic. I looked at AliExpress but they are also expensive there. But there seem to be lots of downloads for 3D printer files. Time to say hi to my friend who has a printer. 
We have a fleet of milling and turning machines) you can make metal from metal, but there are no drawings with dimensions and you cannot get a sample… I would not like to do all this using the poke method…
Some of them do have design files that you could use:
First contact!
Funny how illuminating a real world test can be. Some observations:
- The DE-9 and USB connectors clipped in really snuggly. No external restraint required. The snuggest I’ve ever seen.
- The pin headers were a pain. So easy for one pin to slip lower than another and the hole thing to twist in its holes. Tacking one corner and then refining from there was the best option.
- The dumb MVP was really useful for the JST connectors! Meant I could load all 14 and solder them all in one go. Relatively easy to correct for alignment too using the face available to the side.
- 3D printed PLA is far too slippery on plastic through-hole parts! Maybe some foam would help
- Minor discrepancies in the model can be terminal for this sort of jig - if the height of one feature is too short then the jig won’t fit.
- A nice feature of the jig was that I could really mess up the order of population and get away with it. If I have tall components (even SMD) fitted, I can still fit the jig and do the rest.
This has been an interesting thread to follow. I’m currently working on a project where I’m going to need to do something similar for connectors, buttons, and LEDs. (thankfully everything else is SMD)
My current thoughts are to do a hybrid of the various methods mentioned above. Some sort of 3D printed jig, but with bits of squishable foam placed in its voids to help with height tolerances and pressure. Then maybe one of those frames on top to help hold everything together.
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