The design of the Sphere-O-Bot is great! Thank you for that! During the assambly with a mixure of remixed files, I had some issues that parts did not fit perfect to the MainFrame. I updated or create the not fitting components. (pic of all modified / new parts)

To control the Eggbot, I use a ArduinoUno with a CNC shield with AT2100 stepper driver.

What you need to create this painting robot:

4x 623ZZ 3x10x4mm 2x Wood screw (3mm; for Pen-Arm) 1x Threaded steel rod (3mmØ,80mm length) 1x compression spring (4,5mmØ, 10 mm length) 2x 1.8deg NEMA 17 Stepper motors + cables 1x SG90 servo 1x Arduino Uno + CNC shield 1x 40mm 5V fan (optional) 2x Stepper motor drivers 1x Power supply 12v 1x 12V DC Plug DC Female Connector 12mm M3 bolts M3 nuts

Assambling is easy. To get it runnung and controled with Inkscape... took me a while...

You can not use the original Sphere-O-Bot firmware, because they use there controler board. I got it running with the EggDuino firmware. But before you upload it, check in the EggDuino.ino file, which board is selectet!!! And may change it to the one you use (here: BOARD_CNCSHIELD). Otherwies you only here a humming of the steppers.

To control, you can use the latest version of Inkscape with the Eggbot plugin (ad-ink_320_r0). I had to change the timings for the servo, thats it.

To see it running is really cool.

Update 08.04.2022: To use sharpie pencels, I upload two adapter one for fine and one for ultra fine. Now you can switch the pencils without recalibrating the arm.