JMDict has 219 entries ending in
込む (including 突っ込む and 落ち込む and 乗り込む), but none for 作り込む.
"作り込む" has definitions in Weblio, Goo, and an English translation on Weblio. It's a single morpheme in UniDic (動詞-一般 (general verb), 五段-マ行 (godan, "ma" column).) The string "作り込む" has ~470'000 hits on Google.
Is this just an incompleteness in JMDict, and should we try to create a new entry? (If I can ask, what definitions would you suggest?)
Or might there be some reason why nobody's created this entry before? Perhaps something violating its editorial policy?