I made a shield from junk. It seems to be pretty effective, so I'm not too ashamed to share it. The detector portion of the shield is built around a 12mm thick tungsten tube. I camped the tube into the middle of a large soup can and then filled the can with lead. This produced a 24mm ring of lead around the tungsten. For the base, I made a mold out of scrap wood. The bottom of the mold would be the top of the base, giving a nice flat surface to work with. The interior of the base was borrowed from John Bell's shield write up. I used 2mm pewter sheet and 22 gauge copper, cut to size on a scroll saw. After all the pieces were cut, the edges were cleaned up on my flat lap.
With my 1 inch NaI (Tl) high sensitivity detector at 400VDC, background is 1.12 counts per second. Some ugly napkin math shows that my shield should be around 4 half value layers for 226Ra. A quick test spectrum of 133Ba showed a prominent Cs x-ray peak, but hardly any peak from lead.
Here is the detector shield
Casting the base
Freed from the mold, a bit of trimming to do
Cutting pewter on the scroll saw
Here is the fitted inner shield. The inner cavity of the base was a little rough from casting, the wood I used burned away more than I expected.
Here is the lid with detector window
Looking down into the base
All of the lead was covered with aluminum tape to keep any dust contained.
