[mrv2k]

If you're running Windows use Henrik's HST Imager command line tool. Set up a script with what you want it to do and run the exe with the script. Job done. I use it to make all the AGS hdf files. My script creates, partitions with PFS3 and formats the hdf file. I can then mount the file in WinUAE and it's ready to use. No formatting or rubbish like that. This is an example script.

# create blank 16gb image with compatible size (cf/sd/ssd friendly)
blank AGS_Pure.hdf 16000000000 --compatible

# initialize rigid disk block
rdb init AGS_Pure.hdf --size 15093500000 --rdb-block-lo 2

# add rdb file system pfs3aio with dos type PDS3
rdb fs add AGS_Pure.hdf pfs3aio PDS3

# add rdb partition of 100mb with device name "DH0" and set bootable
rdb part add AGS_Pure.hdf DH0 PDS3 100mb --bootable

# add rdb partition with device name "DH1"
rdb part add AGS_Pure.hdf DH1 PDS3 *

rdb part update AGS_Pure.hdf 1 --max-transfer 0x1fe00
rdb part update AGS_Pure.hdf 2 --max-transfer 0x1fe00

# format rdb partition number 1 with volume name "Workbench"
rdb part format AGS_Pure.hdf 1 Workbench1

# format rdb partition number 2 with volume name "Work"
rdb part format AGS_Pure.hdf 2 Work1

# initialize master boot record at sector 0
mbr init AGS_Pure.hdf

# add mbr partition of remaining space of type fat32
mbr part add AGS_Pure.hdf fat32 *

# format mbr partition number 1 with label "PC"
mbr part format AGS_Pure.hdf 1 "SHARED1"

# show info
info AGS_Pure.hdf

https://github.com/henrikstengaard/hst-imager