Ahh, just seen these, absolutely love #4, I like the processing.... The rest are pin sharp and great use of DOF but you need to look at your composition a bit, for example #1 could be cropped about halfway down as you only really need to see the top 4/5ths of the nut / ferrofluid, the rest is distracting. My top tip is to use white plastic disposable bowls (from Poundland / Wilkos etc usually found with the paper plates / plastic cutlery) as these contain the mess and also provide a clean backdrop. You can always cut part of the rim off to allow you better access for your lens too!
Carl