Advice on New Robocutters X4

[Clive S]

Ok, as there doesn't appear to be any plans/direction around here, I figure I might as well do it myself as I go along

I think so far you have had plenty of direction but it appears you want to be spoon fed all the way.

MyCNC Custom Build!
I guess the quality and reliability of your output here depends on your skill, design and probably some luck.
No recommended designs available, so you need to design yourself or reverse-engineer/side build from other people's designs.
Likewise no build plans or kits, so you'll need to pick through carefully. Every chance end quality could be much better, but likewise no benefit of mass production (ie testing, iterative improvement etc)
Plans available - No (except from picking through/hybridising multiple plans from forums)
Kits available - No
Prebuilt - No (unless JazzCNC is feeling bored....!)

If you read the build logs you will see there are a great number of recommended design changes from other members whether they are taken it or not is up to the builder.
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I feel insulted that you come up with this attitude. But I wish you all the best in your plight.