Shipbucket

FD scale:
- Night fighter challenge
- Strategic transport aircraft challenge
- Rocket fighter/interceptor/"Wunderwaffe" challenge
- Tanker aircraft challenge
- Heavy tank destroyer challenge (think Ferdinand, Jagdpanther and Jagdtiger)

SB scale
- Ship's boats challenge (this would include multiple entries per person and/or template)
- Space station challenge (Skylab, MIR, ISS and such)
- LST (Landing Ship Tank) challenge
- Assault transport ship challenge
- Fleet oiler challenge

Hi all, thought up some suggestions lately:

FD Scale -
- Nation's First Jet
- Carrier-based (not cringe) military aircraft
- Medium bomber
- Recon aircraft

SB Scale -
- Submarine Chaser
- Motor Torpedo Boat
- Guided Missile Cruiser or Destroyer
- Landing Craft

STRONG avatar VERY powerful

franscale:
fluffy creature
bird
edible lifeforms

fdscale:
first "special armor" tank

spacebucket:
spaceship (again)

SB:
Early Dreadnought
FD:
Early War Fighter
Wheeled Tank
50s Armored Car

Another round o' ideas

SB -
Modern Aircraft carrier
LST ship
Cold War era Merchant Man (tanker, bulk carrier, container, ect)
Interwar era light cruiser

FD -
Early Cold War supersonic strike aircraft
Cold War Carrier based support aircraft (EW, AWAC, ect)
Cold War transport helo
Cold War Turboprop powered aircraft
World War II Tactical Bomber

Export Tank Challenge.

Lightweight Fighter Challenge.

FD challenge.

In the early thirties, Frank Whittle falls seriously ill. His work on Jet engines is delayed by several years, and as a result, so is German work. No functional jets enter service before the end of WWII, and all air battles are fought with prop planes.

Design an "ultimate" prop fighter, serving as your country's main military fighter plane at the onset of the Korean conflict, when the first jet fighters are just entering service.

+1 to MihoshiK's suggestion, been itching to draw a superprop for a while now

A few further suggestions of my own:

FD:
Quite The Package - Create a enhanced armor protection package for an existing (older) vehicle; this can be an open-ended challenge for anything from tanks to APCs to cars (hardkill/softkill/era/etc). Would need to show before/after images I think

Pressed Into Service: Design a modification for an aircraft whose role(s) wasn't originally intended. (ex: passenger aircraft > bomber, fighter > night fighter, fast bomber > recon aircraft).

SB:
Makeover: Design a conversion for an ship either from irl or as it has existed in your AU.

What Coulda Been: Come up with a preliminary design study/never were of an AU ship.

SoBu:
Plot Armor: Design some body armor sets as you see fit (any timeline).

GB:
Damn Shawty: Design a shotgun, seems simple enough right?
First Person Shooter: Come up with a fun/wacky gun design for a fictional main character.

Based on recent discussion in the Discord channel.

SB:
Small Ship for a Small Navy challenge
You are the defense minister for a small country with a small navy (think Azerbaijan, Bulgaria, Brunei, Croatia, Estonia, Namibia, Tunisia). The current navy consists entirely of fast attack craft and patrol boats, all displacing under 500 tonnes. You are proposing a new procurement program: up to 4 ships of a new class, larger than any currently in service but still small enough for your country to afford and operate. The details of this country's security situation are up to you, and so is the ship type (FAC, OPV, minelayer, landing craft, submarine, etc). However, you will have to get this idea past the cabinet/legislature/monarch, and after this class is purchased they will not be able to finance any new warships over 500 tonnes for a long time. So an efficient use of resources is greatly preferred.

Rules:
1) The proposed ship must displace under 3,000 tonnes.
2) The proposed ship must be commissioned into your navy between 1990 and 2030.
3) Used, secondhand ships purchased from other navies are allowed.
4) Ships built or designed in other countries are allowed.
5) Entries which deviate from the spirit of the challenge (spaceships, aircraft, animals, amphibious assault vehicles) are not allowed.