Thanks Terry, Evan, DB, Andy and Kevin.
Andy, I got mine from a very good friend as the local pharmacies will NOT sell it over the counter.
BUT you might try one of the following places:
McMaster-Carr
Medical Needles | Stainless Steel Tubing Fabrication - Vita Needle Co.
SmallParts.com: The Hardware Store for Researchers and Developers
I've never bought directly from them but they look like they have exactly the right sizes. See below for a conversion chart for scales.
There is also a company from Spain called Minimeca Espanola that specializes in small diameter stainless steel rod and tubing. They also have .2mm wire that can be used for rigging WWI aircraft with great success. This can be found at some hobby shops (although I have NEVER seen it).
HYPODERMIC TUBING SCALE CONVERSION CHART
1/72 Scale
Caliber Gauge True tube I.D. Scale I.D.
0.30 33 0.00400 0.00417
0.50 29 0.00700 0.00694
7.62 mm 33 0.00400 0.00417
15 mm - 0.00800 0.00802
20 mm 26 0.01000 0.01094
25 mm 23 0.01300 0.01367
30 mm 22 0.01600 0.01640
1/48 scale
Caliber Gauge True tube I.D. Scale I.D
0.30 30 0.00600 0.00625
0.50 26 0.01000 0.01042
7.62 mm 30 0.00600 0.00625
15 mm -- 0.01200 0.01230
20 mm 22 0.01600 0.01640
25 mm 21 0.02000 0.02051
30 mm 20T, 20 0.026, 0.023 0.02461
1/35 scale
Caliber Gauge True tube I.D. Scale I.D
0.30 27 0.00800 0.00857
0.50 23 0.01300 0.01429
7.62 mm 27 0.00800 0.00857
15 mm -- 0.01600 0.01687
20 mm 20 0.02300 0.02250
25 mm 19 0.02700 0.02812
30 mm N/S 0.03800 0.03375
1/32 scale
Caliber Gauge True tube I.D. Scale I.D
0.30 26 0.01000 0.00938
0.50 27 0.01600 0.01563
7.62 mm 26 0.00900 0.00938
15 mm -- 0.01800 0.01845
20 mm 21-1/2 0.02300 0.02461
25 mm 18 0.03300 0.03076 HTX-18R
30 mm N/S 0.03800 0.03691