Waveguide load / absorber material for 2.4 GHz - low cost!

I am in search for a low-cost, low-power waveguide load/absorber material for termination in the 2.4 GHz range.
Materials like the MF-124 from Laird are by far too expencive for my application.
Ideal would be some material that can be machined to form a wedge.
Does anybody have a hint for me?

Water is cheap. Just make some sort of vent for it to boil off it you hit it with too much power

I'd prefere something solid :)
As far as i know, materials with high magnetic loss tan are usual.
How about materials with high dielectric loss tan?
Except the conductivity, are there any other reasons why they are less common or maybe not recommended?

http://stores.cumingmicrowave-online....com/c-ram-mt/

cut a triangular shaped piece of this stuff, and clue it to stiff cardboard
https://www.amazon.com/Selizo-Sheets...s=carbon+paper