This mod adds a handheld/tool version of Create Aeronautics' Physics Assembler. You can assemble and disassemble your honey-glued contraptions directly from your hotbar.
It's just one item, and it does exactly what you'd expect:
Under the hood, it uses the exact same server-side logic as the standard Aeronautics block, so the results are identical.
Combine a normal Physics Assembler with two Sticks on a diagonal:

If you're in Creative, you'll find it in the Tools & Utilities tab.
Dev note: Unlike the physical block, this handheld tool snaps your physics contraption to the grid instantly when you disassemble. Since a held item doesn't have a tick loop, it skips the slow, multi-tick alignment animation the block usually does.
This is an add-on, so you absolutely need Create Aeronautics installed to use it.
Feel free to use my mods in your modpack, just don't forget to give proper credit.
I run these mods together: