Here are the tools I have been using to design and assemble my projects.
Many of them can be replaced by cheaper (or pricier) options, these just happen to be the ones I have.
 

Desk / Design

self-healing cutting mat - insurance for your desk top.

caliper - 3D design usually involved fitting different parts, including components you bought and other parts you design. Precise measurements are necessary to make it work.

head lamp - great for poorly lit desks, and does more than the lamp on the magnifier of the helping hands

scissors - ehh.. for cutting

micro cutter - to clip the tips after solder or pla at an angle

rotex - I got that off eBay, the ones for sale now (like the dymo on amazon) appear to be very poorly build by comparison

safety glasses - after a bit from the dremel split and cracked my regular glasses, decided to buy those and use them when operating anything that spins

dremel - I am not very good at actually using the dremel, but it is pretty helpful for modifying prints without needing to do a full reprint

dremel tungsten bits - those are great to eat through metal.

3D Printing

Prusa MK3s - 3D printer, there are plenty out there. This is the one I have and seems to be ok.

knives to remove supports - better than the x-acto set i have, because the blades are thicker, which comes in handy for prying supports

de-burring tool -great for removing brims on 3d printed parts.

Soldering

soldering iron - There are many out there, pricier and cheaper. This is my third one, and so far is the best. Heats up quick, stays hot. I use it for soldering and for heat inserts.

heat insert tips - they are great to get the heat inserts in PLA/PETG to prepare for the use of screws

helping hands - keep things in place for soldering while your hands deal with the iron and the solder wire

solder reel stand - makes it easy to get the solder wire while holding the hot iron with the other hand

smoke absorber - important if you solder with lead-based tin

wire stripper - you want the one for wires thinner than 20… which I eventually learned means higher numbers

ESD-safe brush - any brush will do to clean dust and remove residue

solder sucker - to remove solder blobs.. 'cause mistakes do happen

pcb vise - that one is a bit of a splurge. It does a great job at holding any pcb during soldering and takes very little space.

iron tip cleaner - it is a bit more convenient to use than the one that came with the iron

Electrical Gear

multi-meter - I use it mainly to test voltages and polarity, but it can also check a few more things.

USB tester - This little dongle checks voltages at USB ports as well as the power consumption.

nitecore battery charger - to charge 18650 batteries

Assembling

screwdriver - any will do, but an electric one makes it easier on your wrist

small bits and sundries electronics tools - they play well with the electric screwdriver

heat gun - I mainly use it for shrinking.. shrink wrap

glue gun - I use it to protect some solder joints and cables from breaking or to add extra isolation so they don't peel off and touch metal parts,