James Willetts, 17, is the first cancer patient in Britain to have the small titanium port bolted to the left side of his head after traditional treatment failed to halt his aggressive brain tumour.
James, from Taunton, Somerset, said: "The first thing that I thought was that I was going to be like Robocop but I actually don't really notice it.
"I can feel it when they connect it but once it has connected it is fine. It doesn't hurt. When they screw it in I can here a scraping noise inside my head."
James is among only three cancer sufferers in the world to receive the treatment - called Convection-enhanced delivery (CEH).
It was created by a 3D printer and has four hair-thin catheters which are inserted into his brain and pointed directly at the tumour.
A plug screwed onto the port allows chemotherapy drugs to be pumped into the tumour with pinpoint accuracy.
It has never previously been used to treat cancer and the £36,000 cost of James' treatment has been paid from donations because the NHS does not provide funding.
James was diagnosed with Glioblastoma in January 2014 after complaining of migraines and stress. He had a 12-hour operation to remove most of a tennis ball-sized tumour which left him with short-term memory loss and restricted use of the left side of his body.
The 3D titanium port was fitted to James' head at Southmead Hospital, Bristol, in late October and treatment began in November.
He has treatment for several hours over two days, after which he is discharged for six weeks before receiving another dose.
James has now received three doses of the chemotherapy and will have a scan next week to find out how he has responded.