Unicomp owns the rights to the design of IBM Model M keyboard, and makes modern version of keyboard with the classic IBM buckling spring key switch mechanism.
[see IBM Model M keyboard]
Unicomp Keyboard Review
Here's a interview with Unicomp guy Mr Muyskens
[Old-School Keyboard Makes Comeback Of Sorts By Mr Muyskens. At http://www.npr.org/templates/story/story.php?storyId=100076874 ]
Here's History of IBM Model M, and Review of Unicomp keyboard.
With APL Layout Keycaps
[see How to Create APL or Math Symbols Keyboard Layout]
The buckling spring is a old tech. There are few other key switch mechanisms with good tactile feedback. If you want something with very crispy tactile bump feel, i recommend keyboard with Cherry MX Blue switch.
[see Guide to Keyboard Key Switch Mechanisms]
[see List of Keyboards with Mechanical Switch]
If you have a question, put $5 at patreon and message me.