You don't need to buy the tool to do a few pins, just small pliers and good glasses.
But that simple crimper is a bit overpriced..
This is a much better tool as it has a rachet action and holds pin better. Its a bit more expensive but if you do any crimping on harnesses, its worth it.
HT-225D-R: Tool Hand Crimp Tool HT-225D Multi-Series Contacts: Jameco Benchpro
D-SUBOPEN BARREL CRIMP TOOL - MT-225D
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I now use a different style connector . It is a one piece with the pins molded in.
Its insulation displacement, but i would suggest adding a tiny bit of solder.
Here are the digikey part#s for them
2pin A31002-ND
3pin A31003-ND
4pin A31004-ND
3-640621-4 TE Connectivity | A31004-ND | DigiKey
Larry