Key binds can always be configured through Minecraft's controls settings. 
 Supports 
Cloth Config and 
Mod Menu for configuration, but neither is required. 
 Options will use their default values if 
Cloth Config is absent. 
 If 
Cloth Config is present, options can be configured either through 
Mod Menu or by editing 
config/meticulous.json in your instance folder (
.minecraft/ by default for the vanilla launcher). 
Key binds
• Toggle; default: m
• Modifier; default: <unbound>
• Always slow modifier; default: <unbound>
• Always slow blocks in list toggle; default: <unbound>
Options
• Enable; default: false
  Main mod toggle. This can be overriden with the modifier keys.
• Notify on toggle; default: true
  Display a message above the hotbar when a key bind toggles the mod or the "Always slow blocks list".
• Minimum time to break first block; default: 10
  Minimum time (in game ticks) it takes to break your first block after you start holding down the attack key   continuously (left click).
• Minimum time to break second block; default: 10
  Minimum time (in game ticks) it takes to break your second block after you start holding down the attack key   continuously (left click).
• Exclude blocks with hardness 0; default: false
  Exclude block that break instantly even with no tool, such as flowers.
• Enable for items:
  Items that Meticulous should affect when you use them to mine.
    • Axes; default: true
    • Hoes; default: true
    • Pickaxes; default: true
    • Shears; default: true
    • Shovels; default: true
    • Swords; default: false
    • Additional items; default: <none>
      Other items that Meticulous should affect that don't fit into the toggleable categories.
    • Excluded items; default: <none>
      Items that Meticulous should not affect even if they fit into the toggleable categories.
• Always slow blocks list; default: <none>
  Blocks that Meticulous should always affect while "Always slow blocks in list" is enabled.
• Always slow blocks in list; default: true
  Toggles the "Always slow blocks list".
• Minimum time to break when "Always slow"; default: 20
  Minimum time (in game ticks) it takes to break blocks in the "Always slow blocks list" or while the   "Always slow modifier" key is held.
 
This mod is only for Fabric (works on Quilt, too!) and I won't be porting it to Forge. The license is MIT, however, so anyone else is free to port it. 
 I'd appreciate links back to this page if you port or otherwise modify this project, but links aren't required.