Good on ya for having a go at this one, I've seen the finished commercial versions on eBay and elsewhere and for what it is their prices were all somewhat over the top.
Trust us DIY'ers to make our own. I'm sure we all have mobs of different sized bolts laying around that we can utilise, I'll certainly be making a few different sized ones for the workbench. Just needed your reminder to get me thinking about this little job I have had on the backburner for so long.
THANKS