Bambu X1/X1C Spool Extender - Compatibility tweaks

Remixed geometry from ttoadd's spool extender, credits to them:

https://www.printables.com/model/338553-bambu-x1x1c-spool-extender

Extends the spool holder out to allow for the AMS to stay plugged in while you use it. Can be used in conjunction with thrutheframe's improved spool holder: 

https://www.printables.com/model/278580-bambu-lab-spool-roller

Print settings

I used Bambu lab default 0.2 strength profile, ABS material. Should work with most other materials as well.

Required hardware:

• 2pcs of M3 x 30mm screws.

What stayed the same:

• Has the same overall length and clearances.
• Requires 2pcs of M3 x 30mm screws.
• Has support ribs that fit around the AMS connector for added stability.

What I changed:

• Added counterbore to second hole as well, so the spool holder can be used in default orientation or upside-down for thrutheframe's spool holder.
• Changed the shape of the support ribs to slope back down at the end. This guides the PTFE-tube to stay in place and not slide off.