AMS riser has a drawer insert option made by tomtom5893. https://makerworld.com/en/models/44128#profileId-45567

You can print in PLA or whatever suits you. 

I have an extruder gear handy as it's a consumable. https://eu.store.bambulab.com/en-ro/collections/spare-parts-extruder-parts-x1-series/products/hardened-steel-extruder-gear-assembly

I needed an insert for it. In spare space I made a few wholes for PTFE tube couplers. The black ones are from aliexpress. 

The blue ones are original bambulab https://eu.store.bambulab.com/en-ro/collections/spare-parts-ptfe-tubing-x1-series/products/ptfe-tube-coupler

https://eu.store.bambulab.com/en-ro/collections/spare-parts-extruder-parts-x1-series/products/hardened-steel-extruder-gear-assembly