Is there a step by step guide on how to start your own bundler to mine / forge child chain coins on Ardor? Do you need to run your own server to do this or can you just login to a public node?
From the wallet cogwheel menu select the bundlers page and start a bundler. You will need to specify your passphrase in order to run a bundler so you'll have to run it on your own node. You also need the node admin password in order to list the bundlers. Here is some additional discussion https://nxtforum.org/general-discussion/ardor-child-chain-bundler-questions/