Edit - I've used this for six months now and I don't have any desire to redesign stuff. It's worked out really well! My Hakko does not come out nearly as much with this solution at hand for small projects.
This is a Pinecil case I designed using the initial box from @Whity parametric box. I changed the hinges so the lid can wrap around and stack under the main box to minimize the space this takes up on your work surface. There are also four rubber feet locations in the lid so your solder iron holder does not slide around.
10mm diameter rubber bumpers - https://www.amazon.com/gp/product/B00K6RZ9Q2/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1
The case has two options that vary by 10mm. The longer case holds the iron in one piece with room for another tip below(offered due to user feedback :) ). The shorter case holds the iron without tip in place for a more compact case(original design).
The lid has a few options below. A plain lid design and one with tabs that stick out to hold a cord. Print those with supports internally. There are also separate cord tabs you can glue on to the plain lid later if you decide you want that functionality later.
For the base…
There is a TPU soldering iron holder which must be printed in TPU to be functional(needs a little flex).
There's also a soldering iron holder arm which uses a 608 bearing(generic skateboard, roller blade, scooter bearing) for the heat break to hold your iron. Salvage from an old skate or get cheap on Ebay/Amazon. Don't need high-end/new for this. I removed the bearing protectors to minimize heat conduction and cleaned out the grease with hot soapy water so it won't get heated up and leak out/smell. This arm sits over a brass/copper sponge so solder drips are caught.
Both options above need to be glued in to place in the base. Using a few drops of CA glue on the pieces and a small spritz of CA kicker on the box surface works great for a quick install.
Hardware required:
(8) 30mm M3 screws which self-tap to secure.
(1) 20mm M3 screw to secure the iron holding arm.
The author remixed this model.
Changed the hinges to longer versions so the lid can wrap around and sit under the base to take up less desktop space.