I am using as below and it fits great

90 Degree 3.5mm 3/4 Pole Male TRS to TRRS 3.5/2.5mm 3/4 Pole Male/Female Headphone Stereo Audio AUX Spring Coiled Spiral Cable https://a.aliexpress.com/_ExZnWb7

I am using MCC from Moergo Glove80 with convex 1u in thumb cluster - should work for double press of adjacent keys and steno mode. Besides, POM is pleasant material. https://www.moergo.com/collections/moergo-keycap-collection

Hi, I am using Fellowes Crystal 9112301 - generally good and comfortable. Common and easy to buy everywhere, but it is worth checking the prices, because there are differences between suppliers.