I'm from Israel, and i love your site.
i've already built several projects from your plans, but this one was the most challenging one.
I wanted the bed to support a mattress (without a base), so i had to modify the plans. I've added 2X4 to the siderailes, between the headboard legs, and to the footboard, and also one in the middle (see attached photos) to support the thin 1X3's that are the base for the mattress.
I painted it using a water based yellowish cream collor (I know that water based color in not the best choice, but it's just so easy to clean ).
I used a Wagner electric spray painter/gun to paint the bed, and the result was very satisfying.
the wood i used was pine.