How to create container template without using the pre-made template

[proxymoxy12]

Hello everyone,
I have created a few VM templates from ISO files using packer and the packer proxmox iso plugin.
I did a little bit of research and from what I know there're 2 options to create container template:

1. Using Proxmox web UI
   1. Download a pre-made base/core/minimal container templates (*)
   2. Create a container from the above template
   3. Customise it
   4. Convert it to a container template
2. Some kind of scripting using pct command to automate the first option.

My question is how to create a new container template without using any of pre-made container templates.
Any input/hints is welcome!
Cheers

 

[Gazen]

Use this manual
https://www.reddit.com/r/homelab/comments/5xvfbf/how_to_proxmox_modify_a_ct_container_template/