John:
A visit to your Dentist can add FREE tools to your bench. I went to my dentist recently for a routine cleaning and asked what he did with old tools or outdated tools. When I left I had a fistful or miniature scribing tools and chisels. One is slightly larger than three sewing needle tips wide. If you can't con your dentist out of his/her old tools check the yellow pages for a medical supplier and buy them new.
For a straight edge to guide the scriber I use an eraser template. These can be found at any good office supply store STAPLES, OFFICE DEPOT etc. these are used by drafting offices to correct blueprint mistakes. It a simple flexible aluminum template with different types of cut outs from straight to curved and is about the size of a credit card but half the thickness. Cost is about $1.00 here.
Hope this helps.
Cheers;
Gregory