The most basic way to diy is 1ml syringes for the flavors, 10ml ones for the base (or larger if you make larger quantities), some empty jars with lids, kitchentowell, notebook/Excel sheet, 20ml or 30ml ldpe/hdpe bottles.
Some of my flavors come in dropper bottles, others in needle bottles, some in plain bottles, but you can all put them in syringes like these, they have a resolution of 0.01 ml:
If you have flavors that come in dropper or needle bottles, leave the cap of the syringe on, pull out the plunger and fill. Turn upside down above your base-jar and remove the cap to poor it in. I have a separate, 'dedicated' 1ml syringe for each flavor.
I usually buy high level nic-base and mix it with liters of VG and PG. I always make separate juices from single flavors and mix them when they have steeped enough.
Make sure you write down every mix you make, as precise as you can. Also make notes when vaping it. This will really help you develop your desired mix.
I agree that using a scale is easier, but you need to know the specific weight of each substance if you want it to be precise. Or you could just ignore specific weights and use the scale anyway, eventually you'll find a mix that works ;-)