I'm interested in joining the postcard exchange, but never made postcards. So I wonder what options are available nowadays.
I don't want to use online service like Hallmarks (and I don't have a inkjet printer either), but want make the postcards myself using some of my pinhole images like these:

image004.jpg image009.jpg image011.jpg image020.jpg

Pin_6x17_Fuji_RVP-001.jpg Pin_6x17_Fuji_RVP-003.jpg

Konica_PRO400-landscape-7.jpg Konica_PRO400-1a.jpg

But I have also some monochrome alt-photo process prints (gum, cyanotype, casein, albumen and carbon prints) I would like to reproduce as postcards:
Casein_print_Bert_Kuijer_15jun-13-meeuw.jpg Casein_print_Bert_Kuijer_15jun-13-roos.jpg glass-neg-1928-willow-wrens-birds.jpg

I read some of the threads here but only saw the Ilford postcard paper mentioned.
So, tips are welcome so I can try it myself and maybe join this exchange in the near future.
Thank you,
Bert from Holland