I once made DEST Powder, that was immune to BOMB and DEST, but I think that it was discovered and fixed, or ether I forgot how to make it, but I'll keep it up and someday make it again, then post it here for you to use.
Ok, I will be posting the Beta of it in a day or so. Unfortunately, it is not completely blast proof (Which is impossible unless you use materials such as DMND), and against everything but BOMB. Because of its circular explosion radius, which just destroys any element.
EDIT: I just added a thin (Two block) Layer of PCLN, so that it will block normal explosives, and BOMB, but not DEST.
DEST just eats through PCLN like normal. Also added a bit of PUMP set to -273.15 C, to make a low pressure area for the SHLD.