[HannahF]

The Rule you would want to pay attention to is
[R28]

Bumpers must be constructed as follows (see Figure 4‑4):
D.be covered with a rugged, smooth cloth. The cloth must completely enclose all exposed surfaces of the plywood and pool noodle material. The fabric covering the Bumpers must be a solid red or blue in color. Visually, the red or blue must be as close to the corresponding color in the FIRST logo as reasonable (i.e. to a reasonably astute observer, they appear similar). The only markings permitted on the Bumper fabric cover are the team number

emphasis mine. I personally would not classify duct tape as cloth. Though If you want to be absolutely positive you should ask the Q&A. But I would plan on not being able to use duct tape. You may want to look into using Duck cloth which is a type of canvas material found at most fabric stores.

~Hannah