Haven't looked, but... do we have devices in this book to summon Cold, Lightning, Metal, and Wood Elementals (from FG1)? If not, we might want to create some.
Cold - Cube of ice that magically never melts.
Lightning - a Lightning Jar! Or a Leyden Jar for those of you who know nothing of canning.
Metal - how about a small crucible?
Wood - a wooden whistle or flute
"If more of us valued food and cheer and song above hoarded gold, it would be a merrier world" – Thorin
Cold: A snowglobe with a tiny golem statue in it.
Metal: A hand bell with magic engravings.
Wood: A closed watering can, water the floor and the wood elemental will grow.
Lightning: A lightning-shaped carved fulgurite
I like items that has a fixed number of uses so here are some suggestions of items with limited use :
Necklace of Ice - Jewelry with N detachable icicle shaped gems. Tear off (use up) a gem for each summoning.
Tears of the Green Man - Bag of N large tear shaped seeds. Planting a seed will summon one elemental. Only usable outdoor.
Elemental Coin - The coin will summon an elemental when thrown on the ground (coin disappears after use).
Cool ideas, Borgar, but I'm really looking for the forms of the items that would be equivalent to the standard elemental summoning devices (the Stone of Summoning Earth Elementals, for example). But single-use or limited-use elemental summoning devices are a VERY cool idea that we should explore for the entire range of elementals!
Reading the elemental conjuring magic object...
The idea of these items is that they can "hold" the element that form the elemental, you put the element in the container as part of the activation, except for air elemental that use incense...
A crucible looks good for the metal elemental, the other elements are harder...
Wood: Maybe a container with soil?
Ice: Something that can keep ice from melting like a cooler... or an ice tray?
Lightning: Something like a battery? A dynamo? A lightning rod?
Lightning - glass rod, or a Nikola Tesla inspired/stylized staff.
Wood - I love the idea of a small pot. Get baby groot in pot image in my head. Alternatively, a wooden amulet or bas-relief type sculpture representing yggdrasil
Ice - a geode-like stone that is cold to touch. If broken open, ice crystals instead of gem-like minerals.
Metal - I like the crucible. Alternatively a small blacksmith anvil.