Just thought I'd share my method for preserving my A5000's IDE hard drive, which gives me a working virtual copy of my physical hardware. The method should work with any Acorn-based RISC OS system, although the method may vary slightly.
I'm not saying this is the only (or even best) way of doing this, but it worked for me.
The memory-card aspect of this can probably be skipped if the source drive supports LBA addressing (and you have an ATAPI<>USB converter and/or a PC with an IDE connector), by connecting the original drive to the modern computer via a USB adapter. Mine didn't though, hence this! If it does support LBA mode, skip step 1 and create an image directly from the hard disc in step 2.
Things you'll need:
A working 32 bit Acorn system of some kind, that will accept the original IDE hard drive
A memory card and suitable card-to-IDE adapter (I used Compact Flash as it's essentially an IDE interface in a smaller form factor)
A modern computer (I used a Windows laptop. It's also do-able on Linux / Macos)
Disk imaging software for said modern computer. I used Win32 DiskImager, but you could use dd on Linux/Macos (with caution)
A USB memory card adapter for the modern computer, or some method of attaching the memory card / original drive to the modern system.
An emulator (I'm using Arculator 2.0)
Step 1: Backup the original IDE drive
Connect the source IDE drive and the memory card via its adapter to the IDE bus of a working system. Format the SD card (not the IDE disc!) with a suitable version of !HForm. (I found it easier/safer to format my card on a Raspberry Pi running RISC OS before I started). Choose whether to support long filenames carefully when doing this, ie make sure your host device supports them. Record the cylinders, heads and sectors-per-track values used during the !HForm process (eg 933/16/63). It's probably best to enable LBA mode if prompted (I don't think the RPi version does prompt though).
On the host device, copy the contents of your IDE drive to the memory card by whatever means suits best (drag and drop worked for me)
Once complete shut down the host device and remove the memory card from the adapter
Step 2: Create an image of the memory card
Connect the memory card to the card reader in the modern computer. Ignore any messages about having to format the card before you can use it.
Using the disk imager of choice (Win32 DiskImager, dd, etc) read the memory card to an image file. With Win32 DiskImager, this is simply a case of choosing the drive letter of the memory card, entering a filename and clicking 'Read'. Give the filename the extension the emulator uses for hard disk files (Arculator uses .HDF).
Wait for the memory card / IDE drive to be read, and (optionally) eject / remove it once complete.
(Optional) Create a backup the image file and/or archive it to somewhere safe (eg cloud storage)
Step 3: Create the virtual machine
In the emulator of your choice, create (or edit) a virtual machine to your specifications. I pushed the boat out and created a 16Mb, fully loaded A5000
For the emulator's hard disk, choose the image file you created in Step 2. If prompted, specify / confirm the cylinders, heads and sector values you used during the !HForm process.
Start the emulator.
Use !Configure to set the number of IDE discs as required, as well as any other preferred settings (eg FileSystem ADFS, Drive 4, Boot).
Reboot the emulator.
Enjoy.