Not all IBM beam spring keyboards have half-height convex modes. Some keyboards have full-height mods. Some have both high and half-height keys on the bottom row.facetsesame wrote: ↑Half height convex mods (as on the Wang 724 and beam springs) are nice, incentivising use of the thumbs while being distinct from the space bar.
The Wang keyboard's keys look almost as reverse space bar profile to me.
Something like this pre-chiclet Apple USB keyboard, I would recon... The "sphericalness" looks pretty mild on these..facetsesame wrote: ↑If the toolmaker me was intent on convex throughout, I'd like to see what the numpad vertical enter would look like!
Another option would be a hybrid, like this Shift key on a µTron keyboard (space bar row, cylindrical alphanumeric keys): On this and older Tron keyboards, the thumb keys are not so rounded but more flat with rounded edges.