I've always loved the paxels from Mekanism, but always thought, what if there was a TCon paxel so I could go about repairing, and adding modifiers to them. I hope this suggestion is taken into consideration :)

By paxel I assume you mean a tool that is an axe, pickaxe, and shovel? I personally really dislike those, as they remove the use of crafting any other tools. I don't like mod content that just serves to make other content in the same mod useless.

Tinkers construct already has many multitool options with an interesting downside:

• The mattock breaks most dirt and wood quicker, but does not have either one's harvest level.
• The blasting modifier that makes tools work on all blocks in exchange for decreased drop rate.
• Offhand harvesting which will use the tool in your offhand if its applicable.

I encourage you to tinker with a few of those options rather than trying to jump to an ultimate tool.