Yes. I have not worked on the 2 my father-in-law has since he passed.
I still remember things about them as I work a lot with them.
Some of the big things for you are do you have electrical tracing skills? CNC skills (to cut molds)? etc. I would recommend aluminum for the molds to start.
Also your knowledge about plastic injection molds is also a key here.
Many of them seem to be reworked and the controls seem to be whatever the owner came up with.
The worst you can do is fire away.
Remember the mold size is around 4" by 5" or so. It will have to fit between the tie bars.
The machines can use up a lot of air if you are running as a production run. My father-in-law had a large air compressor so that was not a problem for us.