I've been wanting a skull shaped Gear knob since I first bought my van but unfortunately my vehicle uses a lift up collar on the gear shaft to move into reverse. Most custom gear knobs aren't compatible with lift-up shifters so I decided to make my own. My van is a Renault Kangoo but most Renaults have the same gear knob arrangement.
Step 1: Removing the factory gear knob
The factory gear knob is just glued in place but my van is about 13 years old so i managed to twist it off without too much of a fight. Apparently they can sometimes be a bit more stubborn but a hacksaw would make short work of it.
Once it is removed you can start to get an idea of the size of the holes you will need to drill in you new knob.
I measured the width and depth of the holes. I decided to keep hold of the factory gear knob just in case I want to sell my van at some point.
Next I worked out what sort of angle I wanted the skull to be positioned at.
Step 2: Planning the Hole
You will need two drill bits. One will need to be the same width as the large hole which the reverse cuff slides into. In this case it is 25mm. You will also need one which is the same width as the actual gear column. In this case 12mm.
You will also need to measure the depth of your chosen object to make sure you're not going to accidentally drill right through it.
I have chosen a Nemesis Now Resin Skull (Azurite Skull) Here is a website which sells various colours and sizes...
I don't own a vice so I drilled a hole in a small section of wood then popped some blu-tac in it. This acts as a support to help you accurately drill the hole.
Step 3: Drilling
This skull is made of resin which despite feeling rock solid is actually really easy to drill. Ideally I would have used a Drill press but I don't have access to one so I had to do it by hand. Start quite slowly and stop if you think the bit is getting too hot. This bit needs to be really neat to look good so take your time and don't drill too deep.
The flat bit will give you a nice starting point for the smaller drill bit. Use a regular HSS bit to make the smaller hole otherwise it might pop out of the top of the skull. Go slowly to avoid drilling right through.
Neaten up the edges with a small needle file or sand paper.
Step 4: Finishing the cavity
Once the hole is drilled give it a good clean. I washed mine under the tap to remove all the dust with a small paintbrush.
I decided that the cavity was a little bit to visible from the outside of the skull so I neatened it up by applying a thin coat of Epoxy Resin. you could also fix any mistakes or scratches with the same method. It dries totally clear although this will only be necessary if you are using a transparent object.
You can see how much neater it looks in the last photo.
Step 5: Fitting
If you've drilled carefully then it should be a pretty snug fit. I used a small amount of contact adhesive to hold it in place but any glue that remains slightly flexible when dry will work brilliantly. You can use Epoxy Resin although I reckon it'd be nearly impossible to remove if you ever needed to change it.
As you can see the reverse collar moves smoothly into the cavity at the base of the skull.
Obviously you can use this method for all manor of objects. Pool or Billiard balls are another popular choice.