The ODM makes people get airborne, look awesome and contribute to the fight against the enimeys of paradise. But how much does it weigh? People are constantly running with it so I assume it doesn't weigh that much, but I don't think its that light either.
Like few people stated in comments, the information wasnt given to us by the author. But even we ever gt that info from Isayama, it would still b just his speculation
There's a fan-made ODM, you can watch it on youtube. The weight of it was 6.6 lb, but i believe more professional ODM gear would be heavier. But for sake of speculation lets say 6.6 lb is down limit of the ODM weight.
So i tried to figure out what's the upper limit. Anyway, the fact that they can run in this ODM gear is actually very important information. Soldiers can run with a full equipment, right? I googled that US soldier are carrying at average at least 97 pounds, actually more than medieval armors lol. But i don't think its any reliable information, because soldiers are carrying a ton of equipment and ODM gear doesn't have much equipment - it need to be as light as possible. SO maybe a Civil War soldier? He was lighter, he carried about 60 lbs.
But saying the ODM weight something between 7 lb to 60 lb... its still not satisfying answer.
So i tried a different approach. I tried finding oxygen cylinder similar to the one used in ODM gear. https://qd-ruiming.en.made-in-china.com/product/oBaQnSjTVLRE/China-Competitive-Price-Portable-Oxygen-Cylinder-with-Valve.html it weigh 2.8 km (about 6 lbs) (the smallest one) We need two, so it's about 12 lbs
Apparently normal size medieval sword weighs 2.5-3.5 lbs. http://www.thearma.org/essays/weights.htm#.X_DRzzSg9aQ Since we have 8 blades and 2 tilts... lets say we have 2 full weight 3.5 lbs and 6 blades with weight of 2.5 lbs 2x3.5 = 7. 6x2.5 = 15. 7+15 = 22lbs
Lets add all the stripes (I would say max 2 lbs) and the mechanism - 3 lbs.
So my guess is 12+22+2+3= 39 lbs
IN CONCLUSION: Im speculating te weight of ODM is 39 lbs.I might be wrong, but its definitely something between 6.6lbs - 60 lbs.
BUT AGAIN, it's just a speculation and nothing more! x)