I was reading the robot section in the manual and i didn’t find anything about saying that we couldn’t use duct tape on the robot. Are we still not allowed to use duct tape? If so can you leave the section and page in the comments?
If you can’t find a rule about it, then it is legal.
As far as I can tell, it’s legal. However, remember exactly why it was illegal for so many years: FIRST did not want people producing duct-tape robots. If people begin going overboard on usage I’m sure the rule will return. Of course, that’s just my opinion 
It’s been legal since 2009.
There were actually limited opportunities to use it before then. Some years’ rules allowed any adhesive tape as an electrical insulator (2000, for example), while others only permitted electrical tape for that purpose (mid-2000s). Adhesive tape was permitted as a non-structural component in 2008, and occasionally as a label in other years.
Of course, some of those earlier games were subject to highly restrictive parts use rules, where Small Parts was the only legal supplier for most items. Small Parts sells duct tape nowadays, but I’m not sure if they did back then.
The “no tape” rule was dumb, but I’d like to see a return of the “no duct tape” rule. It’s just a sloppy construction method and makes for a rather poor looking finished product. Thankfully I haven’t seen too many teams duct tape their robots together, but it does show up now and then. Remember folks, we’re building robots, not duct work systems.
It would probably work for a team like the Duct Tape Bandits to fit their look but yeah slapping duct tape on the robot isn’t really all that professional to be honest.
Nothing says poor quality like a wrinkle in duct tape.
If we’re concerned about making robots look better designed, I think there are a lot more productive ways to do that than banning duct tape. How about expanding engineering support and/or funding?
I really think a duct tape ban would be a “band aid” solution to a very large problem.