I could definitely make a 4.5x space bar, although making one that matches DSA/DCS/Cherry would take quite a bit more time and effort. Everything in the shop right now is "OEM"/Filco profile, and it might be kind of difficult to make a one-off design in a different profile. But I'm certainly not opposed to making complete sets for different profiles in the future. I have keycap sets with OEM and Cherry profiles, and I believe Signature Plastics posts a lot of good dimensioned drawings online for me to replicate DSA and DCS. I also have a Topre keycap that was generously donated, so I can make those in the future as well.
And thanks for adding me to that list, JaccoW!