So recolored Gadgets with same effect for the first three, fine. Teal Gadget, fine, o.k. effect I guess plus it's a level 4 tuner. Blue Gadget is just a Gadget only Tin Goldfish. Navy Gadget is just a Teal Gadget with an added effect. Gold Gadget...hmmm since he is in the Field Card Zone can he be attacked? If not ATK and DEF is pointless plus there is no way he would be unlimited especially because he is TOO EASY TO SUMMON for that effect he has. Blue Gadget into Teal Gadget or Tin Goldfish into Teal Gadget and you get a card that not only completely blocks the Field Card Zone but also can send one card back into the Deck from the Graveyard and Draw a card or just get an additional special summon.
Your Gadgets are not bad but I'm not a fan of Gadgets personally and that Gold Gadget is too much power for too little cost.
