Oh Yes..i've made a frameless slingshot with 1745 tube be4 it dose get hard to do a full draw, i've also had the tube rolling off the thumb as well i just draw slowerly and pull the tubes be4 making the fork with finger than open up the fork, i've done some "research" that those ready made frameless slingshot tube are mostly between 20 - 22cm see if that helps.
The guy in the video at the first post he call himself 极地老妖 "Polar Demon" he is one of the few that started 无架弹弓 "Frameless Slingshot" with great Consistency & Accuracy, later on he also started producing his own brand of Tubes bands, Flat bands and Pouch as well. I am still experiencing with Frameless Slingshot so i am still a Noob at the moment so far i find Frameless are not as Powerful as Normal Slingshot or may be it's just me? I am still experiencing..lolz
My 1st favorite are the DK_Ergonomic Dancing & both Custom 10mm Ti, 2nd favorite are DK_PIXIU i do like the heavy weight of both Palm Thunder because of the weight @ 260g they are more stable at pull and release, but as they are bigger than other Dankung i do need to put in a bit more effort to hold it securely, DK_Platinum are for collecting i am intended to hunt rabbit with them but not at the moment as i am still working on my skill, i can get 7 out of 10 hits @ around 6m to a 4cm metal target there are still much rooms to improve till i can get 10 out of 10 at 10m to a 4cm metal target.
I see you got a DK's Orangutan how dose it feel and how dose it shot? I may even try asking DK to custom made me one with 9mm 440C stainless steel rod..