Even rarer than the 3 DSC's are the two Navy Crosses awarded to RVN forces for the war.   The remarkable story of one of them is here: https://sof.news/history/a-most-unusual-sea-commando/   Note: The article says he was the only NC but there were two.    

Cobolt Trainer, seen a few over here. Basically parts kits with solid barrels and mock bolts, I don't believe Olympic Arms exist anymore. 

Although this info came from AI I'm pretty sure it's all accurate.   The blue-colored M4 rifles used by the U.S. Air Force are inert training weapons, commonly known as "Blueguns" or "trainer weapons." They are designed to safely replicate the exact weight, balance, and dimensions of a live-fire M4 carbine, allowing Airmen to train without the risks associated with loaded firearms.    Here is a detailed explanation of their purpose and features based on recent developments:   1. Purpose: Safe Training & Familiarization Basic Military Training (BMT): As of August 2024, the Air Force reinstituted the "Trainer Weapon Program," where recruits are issued these inert blue M4s to carry and maintain for seven-and-a-half weeks, enhancing familiarity and building discipline.   Safe Handling: Because they are made of solid, high-impact polyurethane (often reinforced with steel), they cannot fire ammunition, making them ideal for classrooms, barracks, and close-quarters training (CQB).   Muscle Memory: They allow Airmen to practice weapon retention, carrying, and maintenance techniques, ensuring they are comfortable with the weapon before switching to a real one.    2. Physical Characteristics Distinctive Blue Color: The bright blue coloring is used internationally to signal that the item is a non-threatening training tool, reducing risk during force-on-force training exercises.   Realism: While some are all-plastic, professional training M4s from Rings Manufacturing feature steel reinforcements to prevent flexing and accurately mimic the 1:1 scale of a real M4, including accessories like flashlights or optics, if needed.   Inert Parts: They do not have moving parts, meaning the bolt, trigger, and selector switch are generally molded into the structure, preventing them from functioning.   

Good as it gets !

Blue is the color for inert items. I suspect they are used only for training and are probably non-firing.

Say whets the deal with these, Blue Plastic parts, is it an Air Force thing?

Collecting not so much. It age a lot less stigma about it and a lot of people whether serious or not collect militaria or trinkets even if there not all I. So most people understand it if you explain it.

Collecting not so much but reenacting yes. I’d say 90% of reenactors are weird as hell. At least in today’s day and age. Most people nowadays have some sort of ideological background rather than just thinking the stuff is neat. Whether it be US, Russian, German etc. it’s gotten bad. And finding  good group of regular people is difficult. I myself got lucky.

Once as a kid back in the 1970s, I saw an old electric chair for sale in an antique store.  My brother and I begged my mom to buy it to no avail.  Talk about ghosts!

This is one of my favorites.  The helmet is an M1-C, FS, SS Rim, with a heat lot number of 883.  The liner is an Inland.  The net is, I believe, a Canadian tri-color.