There seems to be quite a few of now who are either scratch building or adding additional details to existing models/kit builds. A gent posted these on the Gauge O Guild forum last year but I have only just got around to buying some. When you add stubs of wire to replicate bolts or rivets they are most times difficult to clean up and make the heads look respectable. These concave cup cutters allow you to pop them on give them a twist or two and the head is clean and rounded. David Smith the gent that posted them had mounted his in a short lenth of dowel to aid gripping them. Something I am sure that I will follow Cup concave cutters are available from Cousins (www.cousinsuk.com/product/cup-concave-cutter-maillefer-s); the smaller sizes (0.8 – 2.3mm) are less than £2 each. In order to buy you have to create an account but that's no hardship. The site is quite sophisticated as websites go it even has a facility to scan your credit card with your mobile to save typing in the details manually. The other clever thing is that as you add items to your basket it automatically calculates the weight of your order and offers multiple postage choices. for my 4 burrs it was £2.95 P&P What I did note was that on a couple of the smaller sizes (I bought 0.8 and 1.2mm sizes) it's only pence more to buy two than it is one so I got two of each size. Beware not all of them drop down so much for multiples.