I want to make a part with 3mm thickness aluminum plate (about 10 by 10 cm).
On my first try, I painted the plate with permanent ink and drew the layout using a tungsten pen and a square ruler.
After having made a cross mark, I used a center punch, took it to my drill press, and started drilling with a 3mm drill bit at first, then a 5mm drill bit.
On my second try, I printed my layout and stuck it to the plate with latex glue, then used the center punch on the paper, and used the drill press just like during my first try.
My first try lacked precision due to the imprecision of my hand and ruler.
During both of my attempts I also had a problem with the drill press as I wasn't able to position the center punch mark to the drill bit accurately enough.
My drilled holes are usually off-center by almost a millimeter.
I usually make my part with a 3D printer. This metal working is quite new to me.
Am I missing anything? How should I have done this?