Update
Added updated model and instructions for A1 Mini. Skip to the bottom for install directions

Got tired of constantly bumping into my old desk cup holder so I designed one that not only pulls out from under the desk but is retractable as well.

The retracted cup itself measures roughly

75 mm deep

94 mm wide top

81 mm wide bottom

Because of the retractable nature of the holder I wasn't able to design it with a cutout for coffee mug handles sadly but, it will accept most normal glasses, bottles, even my 30oz Stanley water Cooler.

The holder is designed with 3, 6mm x 3mm magnet holes. The magnets aren't required but do give the holder a satisfying “snap into place” feel when you're deploying or retracting the cup holder away.

These are the magnets I use
https://www.amazon.com/gp/product/B096LZNZTQ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Installation Instructions

Optional step

Install the 3m x 6m magnets in the cup holder (1x) and cup holder sleave (2x). The magnets should fit in pretty snuggly. You may want something hard and flat to use to fully press them in.

Step 1.
Print out the guide included in the project. From there, place the guide on the underside of your desk where you'd like the cup holder to go and make sure it's hooks are flush with the front of the desk. Mark the 4 mounting holes

Step 2.

Put the cup holder in the Cup holder sleave. Line the mounting holes up with your marks and check that the unit lines up with your desk correctly. A correct install will have the edge of the cup holder almost flush with the edge of your desk.

Step 3.

Remove the cup holder and line up the Cup holder sleave mounting holes with your marks. Use 4 screws to attach through the mounting holes

Step 4.

Re-insert the cup holder and screw the printed Bolt up through the bottom bolt hole. This bolt makes sure that your cupholder doesn't slide out of the sleave when you pull it out.

Step 5.

Retract the holder and begin your new cup holding journey! If you need to remove your cupholder for cleaning just unscrew the securing bolt and pull the cupholder free.

Print instructions

The holder itself is 3 pieces

Cup holder

Cup holder sleave

Securing bolt.

With an optional 4th piece which is the mounting guide.

-The Holder and bolt will print out together. The sleave and guide will need to be printed on their own.

-Both the holder and holder sleave are set with 10 mm brims as I was having issues with the filament I was using warping off the bed. If this isn't an issue for you, feel free to turn off brims.

No supports needed and the retractable cupholder is all print in place. Only assembly needed is already noted in the installation guide above

A1 mini install instructions

Disclaimer: While I did print out and test the model for the A1 mini, I do not have the printer (printed on my p1p). I've redesigned it to specifically fit within the A1 mini specs but please let me know if some aspect of the build doesn't work. Also, while I did save the project specifically for an A1 mini, I'm not sure if my p1p AMS settings will mess with anything. So just be sure to double check before printing.

Step 1. 

Download the A1 mini project file

Step 2. 

Print out the model broken into 3 plates. The cup holder, the sleave, and the 2 locking bolts.

Step 3. 

(optional) Install the three, 3mm x 6mm magnets. 1 on the cup holder and 2 on the sleave. They should fit snuggly but if they are a little loose, i recommend a dab of super glue to keep them in tight. 

As noted above, these are the magnets I use
https://www.amazon.com/gp/product/B096LZNZTQ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Step 4. 

Place the sleave on the underside of your desk where you'd like to install. Make sure that the front “struts” are flush with the edge of your desk

Front studs flush

Step 5. 

While holding the sleave in place, slide the cup holder in to verify that it's fully under the desk when in the sleave

Step 6. 

Remove the cup holder and use 4 screws to mount the sleave to the desk.

Step 7. 

Slide the cupholder back in and screw in the 2 locking bolts on either side of the sleave. If you need to remove the cupholder for cleaning, simply unscrew the locking bolts.

That's it, get to cup holding!

This has been working out great for me, hopefully its equally helpful for you!
Happy Printing!