I wanted to replace the original hard drive in my classic Macintosh G4 Cube. Looking at the current offerings they had several deficiencies in form or function. So I took a stab at it.

I remixed the bracket from:
Laptop IDE to Desktop PC Adapter, 2.5 inch 44 Pin HDD Hard Disk Drive or SSD to 40 Pin 3.5 inch PATA Port Converter Card
https://www.thingiverse.com/thing:656966

This updated drive bracket lets one use the original mounting hardware and fits perfectly with existing cabling. Also, you will be able to close the airport card door without issues. To use this bracket, it needs the following pieces of hardware:

 1. Godshark Laptop SATA to IDE Adapter, Convert 2.5 Inch Serial ATA HDD Hard Disk Drive or SSD to 44 Pin Male PATA Port

2. Godshark Laptop IDE to Desktop PC Adapter, 2.5 inch 44 Pin HDD Hard Disk Drive or SSD to 40 Pin 3.5 inch PATA Port Converter Card

3. For the SSD, I used the 120GB OWC Mercury Electra 6G (could probably use other SSD's, but I have not tested other brands)

All are available on Amazon.

Combine the devices an connect to the SSD. I used Kapton tape to cover the electronics. This combo also allows the G4 Cube to boot in System 9 and the built in DVD drive also works fine.