This is a share of Alvaro Alea Fdz.'s project, originally published at https://github.com/alvaroalea/QL_CST_FLoppyController — all credit for the design work goes to him. CST was one of the main add-on manufacturers for the Sinclair QL, and their floppy disk interface went through several revisions with improving compatibility. This repository recreates Issue 3 (ROM v1.16, 8Kb) and Issue 4 (ROM v1.18, 12Kb in a 16Kb EPROM, with a RAM disk driver) as full KiCad projects, with schematics captured from photographs of surviving original boards. Both designs use a WD1770 floppy disk controller and a standard Shugart connector, supporting up to two drives configured as DS0 and DS1. The WD1772 is expected to work as a substitute; the WD1773 is not compatible. Fabrication Gerbers are supplied ready to order from five different PCB houses, alongside a 3D-printable enclosure. Both boards are entirely through-hole — 31 parts on Issue 4, 25 on Issue 3 — making them practical to assemble by hand. One warning from the original author worth repeating: unbranded bulk 2N2222 transistors tested fine in isolation but caused compatibility problems with other expansion boards, so use a reputable source for Q1. ROM v1.19 remains missing; other versions are available from Dilwyn Jones's QL archive.