Non exhaustive list of still somewhat alive 3D-H movie circles as of March 2018.
@OZ: http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG08239.html
14rabbits: http://www.14rabbits.dojin.com/
365%: http://365percent.xyz/
A4 Production: http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG37229.html
Almond Collective (アーモンドコレクティブ): http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG09062.html
A Third Dimension: http://atd2010.blog33.fc2.com/
Amelialtie: http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG25779.html
Atelier KOB (アトリエこぶ): http://b.dlsite.net/RG05995/
BISHOP: http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG02834.html
Blue Arrow Garden: http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG19442.html
Cute Cats: http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG39239.html
Demodemon (デモデモン): http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG06013.html
Doll House (ドールハウス): http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG02782.html
Double Soft Cream: http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG02138.html
Doujin3aries: http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG03711.html
Edge Systems: http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG03942.html; iLand: http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG39589.html; Final Fuck 7: http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG07183.html (same circle, different themes)
Gomasen (ごません(3D): http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG06256.html
Gomasioken (ごま塩犬): http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG23835.html; http://b.dlsite.net/RG23835/
Green Curry (グリーンカレー): http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG28883 (previously known as TYS Work: http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG16158.html)
Hananoyousei (華の妖精): http://hananoyousei.x.fc2.com/
IMP: http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG22172.html
Ivory Tower: https://www.dlsite.com/maniax/circle/profile/=/maker_id/RG08568.html
Joy's Shop (喜’s屋): http://yorozyablog.blog.fc2.com/
KENZsoft: http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG09414.html
Mi Po Z (みポZ): https://www.dlsite.com/maniax/circle/profile/=/maker_id/RG13735.html
Kuril (くりる): http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG10411.html/
Marmalade Star (マーマレード★スター): http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG13685.html
Miconisomi (みこにそみ): http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG16690.html
Mimia Cute (futa/dickgirl works) /Potato Mine ("straight" works): http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG21792.html and http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG31971.html
Otemotoya (おてもと屋): http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG13369.html; http://otemotoya.sakura.ne.jp/top.html
PeD: http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG27039.html
POCOMOPREMIUM (ぽこもぷれみあむ): http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG24451.html
Pompurin (ぽんぷりん): http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG03522.html
Rainbow Bambi (にじいろばんび): http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG17968
Rifle (possible romanisation of リフル): http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG39492.html
Ribbon Frill: (リボンフリル): http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG02369.html
SakamotoJ: http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG11358.html; http://sakamoto3d.blog113.fc2.com/
Sandwich Works (さんどいっちわーくす): http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG19360.html
Seismic: http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG12892.html
Shizukugumi (雫組): http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG02935.html
Socrates: http://c-socrates.sakura.ne.jp/index
Stborough Ag Seirenjo (スタンブローAg精錬所): http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG10138.html
Studio GGB: http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG13002.html
Studio Izumo: http://studioizumo.blog.fc2.com/
SYLD: http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG05012.html
Tofu Soft: http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG20421.html
Umemaro3D (梅麻呂3D): http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG01865.html
Wantan Works: http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG06281.html
Yosino: http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG02662.html
Yuuei Studio (遊泳スタジオ): http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG11009.html; http://yuueistudio.x.fc2.com/top.html
Zero-One (ゼロワン): http://www.dlsite.com/maniax/circle/profile/=/maker_id/RG03720.html