I know I could have found what I was looking for online but the shipping times and prices combined with the fact I wanted to make it now made that option rather unappealing.
I did of course manage to track down stretch lace and strapping in white and some navy dye (after some hunting!). So I got stuck in and am quite pleased with the results.
I did a little bit of googling and found this post by Dana Made It about dying elastic so I went for it.
I was recommended to use Idye Poly by the girl in Lincraft, however it didn't come in Navy. I grabbed a bottle (as per Dana's post) of Rit Dye in navy and took a leap of faith.
I had five metres of lace and a metre of the strapping in 1/2 a bucket of water (about 5 litres) and half a bottle of dye.
The instructions said to stir continuously for 30-60 minutes. As if that was going to happen! I stirred it every 5 minutes for about a minute each time for about 35-40 minutes before pulling it out.
This was the result as I pulled it out of the dye. You can see the fold over elastic I was trying to match on the right so I thought I was pretty close. However after running it through the washing machine (as per instructions) the results were a little different.
As you can see the colours did change after they were washed. They became a little more royal than Navy. I probably should have kept them in for longer, or just dyed some fold over elastic instead of trying to match it to pre dyed elastic. The strapping seemed to hold the dye better than the lace did, but they did still turn out quite well for a first attempt. I'm sure this won't be my last.
Overall I highly recommend Rit liquid dye, even for the price (I think I paid about $19 a bottle at Lincraft). It was an easy process to follow and had good results even on non cotton materials.