While in any armor configuration the Tremorsense extends to 30'. The armor is treated in all ways like the armor named in parenthesis, save that it is non-metallic and adds no additional weight to the character's encumberance total. No attacker may flank the wearer unless more than 15' away without first rolling a successful Move Silently check.ДЄs a move-equivalent action the wearer may command the cummerbund to grow into one of three armor types of light, (padded,) medium, (breastplate,) or heavy, (half-plate,) configurations. When first donned the cummerbund grants the wearer 15' tremorsense. It has been enspelled to offer a variety of levels of protection for the wearer, and it retains some of the abilities of the original worm. What appears to be a purple cummerbund or girdle is a living fragment of a purple worm. If crafted by an incredibly skillful (or lucky) craftsman, the bonus given by these items are doubled and their rarities increases by one level. Additionally, attuning to this armor has connected your mind to the remaining nervous tissue within the armor you gain Tremorsense out to a range of 15 feet. While wearing and attuned to this armor, your AC, Strength score, and Constitution score increase by 1. Additionally, if you have an ability that allows you to use shields as weapons you gain a +1 to attack and damage rolls made with it.ДЄrmor (Scale, Breastplate, Half Plate, Plate), Very Rare (requires attunement)Д¬rafted from the hide and scales of a Purple Worm, this armor retains some of the essence of the monstrous creature it came from.

While holding this shield you have a +1 bonus to your AC. The warlock is currently wearing a +1 breastplate made from bulette plating.Well, I have a couple ideas. And I have a general understanding that +X items require exotic materials. +2 armor is Very Rare, which is about right for a CR 15 creature. I'm looking for fun, thematic ideas in the Very Rare range. I could be boring and just say '+2', but that's boring. The medium armor is for a hexblade (with some later fighter levels) who mostly melees the shield is for a paladin who has a special ability to use shields offensively (bonus action 1d4+ stat bludgeoning damage, counts as weapon for smite). They now want armor made from them (by an NPC)-specifically breastplate/half-plate and a shield.

My party has defeated a purple worm (CR 15) and taken a chunk of scales.

D&d purple worm