So, I recently had a thought that was something along the lines of what would happen if I made dragonhide armor? Would I get immunity? And starting searching for an answer, to no avail. This also got me wondering if I could use other parts of dragons-and monsters in general-to make weapons in armor; I.e. Dragon teeth gloves, Cloaker wing cloak, Tarrasque bone armor. So then I thought it'd be cool to create a guide on how to make like monster-based tools and how to obtain them. I gave a few examples, but feel free to take this info and apply it to your own campaigns (whether to min-max, annoy your DM with broken stuff at level 3, or to make more fun items for your players).

Dragon Tooth Gloves/Gauntlets. Gauntlets/Gloves adorned with dragon teeth. How to obtain materials: pry out the teeth of a dragon, use random dragon teeth found on the ground or in victims, etc. Buy standard gloves/gauntlets at equipment stores. How to craft: Make a check of your DM's decision (I recommend Wisdom or Intelligence) using Leatherworker's tools or Smith's tools if you are using gloves or gauntlets, respectively. Let your DM decide any additional costs that (s)he deems appropriate. Properties: Whenever you make an attack with this weapon (considered an unarmed strike) the target takes an additional 1d4 piercing damage. In addition, unarmed strikes made with these on are considered magical. Also, they look super cool. Downsides: I can't imagine dragonborn/dragons of any kind are going to be happy you used the teeth of their cousins to make weapons. Let your DM decide what this means (this usually constitutes a disadvantage on Charisma checks).

Cloaker Wing Cloak. A cloak made of a strange leather that comes from the wings of a cloaker. How to obtain materials: Harvest the remains of a Cloaker. Buy an ordinary cloak at an equipment store. How to craft: Make a check of your DM's decision (I recommend Wisdom or Intelligence) using Leatherworker's tools to combine the two materials. Let your DM decide any additional costs that (s)he deems appropriate. Properties: While wearing this cloak, you gain a +1 to AC, assuming you are wearing no armor. In addition, you can cast the mirror image at will as an action on your turn; however, it does require concentration, and the duplicates lack any solidity and interacting with them shows them to be an illusion. Downsides: None that I can imagine. I bet your DM will get really creative while you have this absolutely broken cloak and say that there is some subterranean humanoid cloaker race that now hates you.

Baby Flail Snail Helmet. This helmet was made from the shell of a baby flail snail. How to obtain materials: Find a baby flail snail and kill it. While some of you may find remorse in this, I bet all you min-maxers ot there will kill it and laugh as it dies, just imagining the benefits of wearing its shell. You may also find a helm to fuse it with. How to craft: Make a check of your DM's decision (I recommend Wisdom or Intelligence) either using Woodcarver's tool (if not using a helm) or Smith's tools (if using the helm) to either carve out the shell correctly or to fuse the item with the helm. Properties: If you wear this, you gain the following trait:

Antimagic Shell. You have advantage on saving throws against spells, and any creature making a spell attack against you have disadvantage on the attack roll. If you succeed on the saving throw against a spell or a spell’s attack roll misses it, the shell converts some of the spell’s energy into a burst of destructive force if the spell is of 1st level or higher; each creature within 30 feet of the you must make a DC 15 Constitution saving throw, taking 2 (1d4) force damage per level of the spell on a failed save, or half as much damage on a successful one.

Hope this inspires you. Feel free to comment with your own creations.