That looks great mate. Is it as simple as cutting the bottom off and piercing holes, or is there more to it? I've a few of those bottles lying about so will give it a go.
Pretty simple mate,
The top 40mm of the bottle inverted into the bottom 40mm of the bottle.
Squash the pieces together either in a vice, or in my case, scraps of wood and a few G-clamps.
File the top flush and de-burr the edges.
Pierce 16 holes, I used an old dart. (15mm down from the top)
Masking tape helps protect the paintwork when cutting. And marking the holes evenly
For a bit of shiny bling on the inside, get busy with some very fine wet-n dry and cutting compound (T-cut etc)
And then again with a cloth and cutting compound
Finish with a clean rag.
Have a go !