• AGILE TOOLS, Box 1408, London, NW10 9ES (020-8452 6724). BA taps and dies, nuts and bolts.
• J.A. CREW & CO., Waterygate Farm, Dovers Hill, Chipping Camden, GL55 6QU (01386-841979). Broad range of engineering supplies by mail order at sub-retail prices.
• CARR'S MODELLING PRODUCTS, Unit 5, Centre 88, Elm Grove, Wimbledon, London, SW19 4HE (020-8946 5038, fax 020-8947 7801). General purpose and special solders (even for aluminium and mazak!), soldering tools, metal blackening chemicals.
• CETEM & ABC POLISHING SUPPLIES, 103 Louth Road, Holton Le Clay, Grimsby, NE Lincs. Tel: 01472 824520. Polishing materials and abrasives, mail order catalogue. Web site: www.cetempolishing.co.uk or www.abcpolishing.co.uk  Email:sales@cetempolishing.co.uk
• M. FARRANT, Steinkirk Building, 93 Dunkirk Road, Lincoln, LN1 3JU (01522-542366). Polishing tools and materials for metals, glass and Perspex.
• GFM ENGINEERING, Clayfields, Tickhill Road, Balby, Doncaster, DN4 8QG (01302-859556). Whitworth BSF nuts & bolts.
• HARRIS & WALEY, 17 Lothair Road, Aylestone Park, Leicester, LE2 7QE (0116-283 2970, fax 0116-2440482). Nuts and bolts, screws, fasteners of all kinds.
• NAMRICK - THE NUT & BOLT STORE, 124 Portland Road, Hove, BN3 5QL (01273-779864, fax 01273-726708). Fasteners, tools, washers, sealants, pipes, clips, taps and dies, BA, BSW, Metric, UNC, UNF - you name it! Mail order catalogue. Now you can order fasteners online at: www.namrick.co.uk.
• RESTORATION MATERIALS, Barnside, 194 Wellington Road, Bury, Lancashire, BL9 9AH (0161-764 2741). Web site: www.restoration-materials.co.uk  Full range of clock maker's supplies also applicable to radio cabinet work, including chemicals, lacquers, wood stopping, sealants, adhesives, toners, metal finishes, polishes, shellac and cellulose polishes, solvents, stains, waxes, gums, wire wool and tools.
• A. & R. SHELDON, 33 Bramhall Park Road, Bramhall, Stockport, SK7 3JN (tel/fax 0161-440 0821). Comprehensive mail order catalogue of engineer's and automotive tools.
• SMALL PARTS, Inc. Miami, Florida, USA (00 1 305 751 0856). Knurled screws in brass and nylon plus lots of other interesting items.
• STOCK DRIVE PRODUCTS. Stock Drive Products/Sterling Instrument.Stock Drive Products / Sterling Instrument, 2101 Jericho Turnpike, Box 5416, New Hyde Park, NY 11042-5416, USA. They carry all sorts of gears, mechanisms, timing belts, flexible couplings, etc. They are a must for homebrewers. Request their catalogues from: http://www.sdp-si.com/catalogs.htm or by post.
• John SWINGEWOOD, 5 Blaze Park, Wallheath, DY6 0LL (01384-401135, fax 01384-292110, g4cvu@hotmail.com). Makes replica Bakelite knobs to order using your original to make the mould. Produces turned brass inserts and other custom metal work.

NB: for square section wire try the better hobby shops, some of which sell brass profile sections for model boat and train constructors. Sheet copper of various thicknesses is available in art/craft stores where they sell copper enamelling supplies.Another source is any place where they make copper gutters or roofs-you should be able to get scraps for little or nothing. Sheet brass and nickel silver can be had from good model railway and model boatbuilding shops; see your local Yellow Pages or the advertisements in a specialist hobby magazine.

A source of loose bearing balls (for ball races in tuning dials and so on) is your local bicycle repair shop; they are typically stocked in 1/8, 3/32 and ¼-inch sizes. Failing this, there are specialist ball bearing supply houses in larger towns (see 'bearings'in Yellow Pages).