Eyepieces need cases, but it’s expensive to buy a bunch of different sizes for different size eyepieces, particularly for 2” “hand grenade” sized eyepieces like the 18mm TeleVue Nagler and 56mm Super Plossl pictured. So rather than spend $10US per case (plus shipping!) I used Autodesk Fusion 360 to make my own and print them with my 3D printer!
Creating the design is super simple – for the bottom create a series of concentric circles starting with the narrowest size of the interior of the case (say 70mm) then a second circle 4mm larger (74mm) which is the wall of the case.
For the top create a second circle with the first inner circle 1/2mm larger than the outer wall of the bottom (74.5mm) and a 4mm wall (78.5mm)
Finally use the Extrude function to first raise the inside circles 4mm to form the lid of the item, and then extrude the sides up as far as you need them (say 100mm for a tall eyepiece). Save as STL files, and print. The largest eyepiece containers took 13 hours total to print and used about 200g of material, for a total cost of about $5.59 per eyepiece container. Anything I design for 3D printing will be posted on a new section of my website for free use by anyone. The address is: http://3.99.76.122/3d-printing-for-astronomers/. Autodesk Fusion 360 is free for hobby users at: https://www.autodesk.ca/en/products/fusion-360/personal