Hi, Yes, we have experimented with bigger arms, although we’ve always made both arms bigger. As you say, you’ll get a bigger drawing area with a little less accuracy. Pen weight will also become more significant as you lengthen the arm so you may need to consider that. Also the weight of the extension will contribute of course. The firmware limits the arm movement so that it doesn’t hit the body of the machine, but with a longer arm there may be some areas where there’s a chance that the extension might hit the machine body so do be a bit careful with that.
I’ll be interested to hear how you do the mapping - we calculate the angles based on the pen position using the intersection of two circles (which in your case would be different radii) and you could then calculate the pen position for the ‘normal’ arm that you need to send to the machine easily from those angles, but it seems like there ought to be a more elegant solution than that…?
Let us know how you get on - what language are you planning to use?