Scrap Trawler is a very powerful card. Combos with
Krark-Clan Ironworks and
Myr Retriever? TBH, even though I run it in my Sharuum deck, I won't claim to actually understand how that particular combo works. Most of the time, I just use it as a value engine - my deck isn't particularly built around it (I don't have a ton of self-sacrificing artifacts or 0-drops to recur), but it is still a good way to recur a few cards. The fact that Sharuum is a 6-drop and thus can recur most of the artifacts in my deck on death certainly helps.
More broadly, Scrap Trawler is great in decks with lots of cheap artifacts, particularly if you have ways to sacrifice them. Chaining something like
Hedron Archive →
Commander's Sphere →
Mind Stone →
Nihil Spellbomb →
Lotus Petal represents a ton of value. On the other hand, if you're using it just as a bigger Myr Retriever and don't expect to get any triggers off of things other than itself, it goes down in value significantly. I won't say it is an autoinclude in artifact-based decks, but it's pretty much always worth consideration.