[Elecraft] OT: heat sinking resistors

[Vic Rosenthal]

I apologize in advance, but the smartest guys I know are here.

I just received a few Ohmite thick film power resistors for an attenuator I'm making, 
rated 20 watts. They are 15mm x 10mm x 3mm. Obviously they have to be heat-sunk 
(heat-sinked?) if they are going to dissipate that much power.

How do you do this? There's no hole in the middle...I can just clamp them between a couple 
of pieces of aluminum, but is there a right way to accomplish this?
-- 
Vic