Poor mechanical design
340338
The coupling hole diameter is .0815" (2.07mm) while my motor shaft is .0790" (2.00mm) --a diameter difference of .0025" (.07mm). The two set screw holes are located 180-degrees from one another.  That means the shaft is suspended at two points within the coupling that allows the coupling to pivot on the common axis of the two set screw holes when the motor is operated.  Poor (sloppy) design.  Hole diameter should less than .001" (0.025mm) of the motor's  shaft (diameter) to prevent excessive wobble, and the set screw holes should be located 90-degrees from one another to avoid pivoting.  .
The same problem for the larger coupling hole -- too large, and incorrect angular placement of the set screw holes.
 Couplings are worthless for my high speed (RPM) motors.
718327
Took it out the box and pulled back one of the spring loaded slots to put a AA battery in, and PING, the thing broke before I even got a chance to use it.  The other 3 slots are still working and I tried pulling them just to make sure the same thing wouldn't happen, but this is extremely disappointing.  I would not recommend this thing.  Weak design.
976538
Surprisingly poor function.  Mounted to Remington 870 12 Ga. with vent rib barrel - new out of box.  One of the more common shotguns on the market.

Worth mention: 10 years working in law enforcement training group, no stranger to weapon systems for mounting accessories.  I wasn't looking for anything "high speed/tactical" for this price, just a basic home defense type mount.

Mount did not hold flashlight in stable position even with a few pounds of finger pressure despite multiple adjustments.  Flashlight diameter is within advertised range as is barrel diameter.  Overall poor design both with regard to mounting pads and clamping mechanism.  Clamping mechanism slips and rubber pads do not prevent movement of mount or marring to barrel finish - pads create essentially two opposing points across from each other on a cylinder, much like a pivot.  Clamping mechanism has a slot that allows the threaded clamping rod through center of mount to drift with little pressure.  Between these two design failures, lots of "slop".

Not stable under firing conditions, don't use for anything requiring a reliable light mount.  Taking this off and tossing it before any more of the barrel finish is scratched away.
2295465
The design is poor. Its difficult to set the battery into the charge position because of a sill bulge at the top edge. Its almost impossible lfor the battery to stay connected if upright. You have to stand the charger a an anage or let ti lie flat as it charges the battery. However, the cost is so low that its more than worth putting up with the annoyance.
4839476
When we assembled the product, we had to purchase different screws than the ones the directions had called for because they were too short to be  able to work. This happened on more than one type of hardware for this unit. The pilot holes were over drilled so when we tried tightening anything, it would not get a good grip. The drawer does not slide with ease, you have to pull hard on it because the dimensions in which the door fits in are too small. Overall poor design. Very unsatisfied.
3928246
Poor machining.  Had to rethread in order to get pedals to thread properly.
404367
The mechanical drive unit is sloppy. Have too turn handle three or for times before it starts to turn not what I expected.
1015132
AT FIRST, I wanted to like it.  It seemed unfussy and elegant, and would solve an annoying kitchen problem.  However, mine wouldn't tighten or stand straight.  It was forever a little loose and wobbly and the paper towel roll would not freely spin around the silicone vertical stand.  I took the suggestion offered by the seller in the Q&A section and cut a small hole in the bottom of the rubbery base so that I could tighten the bolt that attached the vertical stand to the base.  This helped a little, but it still would not stand firm.  Finally, as I was tightening the stand for the umpteenth time, it simply popped off.  It turns out that there's just a little metal nut under a stiff rubber ring in the bottom of the vertical stand (see pic); that's the only thing securing the stand to the base.  When my rubber ring snapped, the whole assembly came out of the silicone sleeve.  I'm a strong woman, but I feel that I should be able to hand-tighten my paper towel holder without fear of snapping parts off.  This is just poor design.

HOW I FIXED IT: So now I had a broken paper towel holder, a continuing need for one-handed paper towel tearing, and a reluctance to do a return with an online retailer.  I needed to make this work.  In desperation, I unscrewed the bolt from the base and set it aside, unscrewed the silver topper off the vertical stand, inverted the vertical stand, and screwed the now upside-down vertical stand into the base.  Then I re-used the little metal nut on the bolt sticking out the bottom of the base to tightly secure the vertical stand.  NOW the paper towel holder worked as intended - the base stayed put, the paper towel roll spun smoothly on the vertical stand, and I was able to tear off sheets one-handed.  I couldn't use the silver topper any longer, but I was ok with that.

IN CONCLUSION, if you get a working paper towel holder, then this is the best thing since sliced bread.  However, I believe that this product has a design flaw that sometimes doesn't let the vertical stand get properly tightened onto the base.  If you get a defective one, then you can use my simple workaround to avoid a return, or just do the return.

NOTE: Some reviewers complained about having to unscrew the silver topper in order to switch paper towel rolls, but I did not need to do that at all (when I was using the silver topper).  My Bounty Select-A-Size rolls from Costco slipped on and off just fine.
4918374
The clamp is poorly designed. There is a little nut inside the housing (diificult to see from the picture) that the bolt screws into. The nut was floating around in the housing and takes a lot of time and effort to thread the bolt into the nut because it keeps moving around inside.
Second is the clamp doesn't adjust much wider than shown and my handlebars are too thick for the clamp.
Its a good idea but the clamp tightening mechanism is flimsy and frustrating and rigid specs around the width you can clamp this device too makes it so I cannot recommend this to others.
3681626
In my opinion, this is a poorly designed product. It has a plastic cam that couldn't take the pressure of my light usage for my Fox Vanilla Air RC shock.  It broke a the hub, a hex-design that is weak and can not take the pressure of  to torsion to pull the cable and lockout the shock  For the price being charged, the cam should be made of metal.  I am an inventor having created and offered a fantastic screen door closer; please see [...].  I therefore have the credentials to criticize the Rockshox Pushloc as having a weakened and poorly designed mechanical flaw!
2065238
Like most JK owners, the OEM latches began to sun fade and would loose the ability to keep the hood from fluttering in windy conditions. So after some research, I chose these latches because of their look and design. Boy was I disappointed.  The concept is good, but a total failure in design. They were easy to install, but would not latch properly no matter how you adjusted them. The problem is the latch bottoms out on the catch before it can completely cam over and latch properly. And then they expect a little piece of plastic to keep it latched closed!  They really need to look at the geometry of these latches taking in to account manufacturing tolerances. I ended up throwing them in the garbage and buying some new OEM latches. I would not recommend these. (Yes.  Im a mechanical engineer. )
4032689
Great idea with poor design choices. It's too loud as built and distracts from the environment. Remember, this thing is intended to soothe, lol.

The air pump causes a lot of vibrations and as the air pump is at the bottom of a long tube, the thing acts a bit like a pipe/organ.

I fixed some of that by putting a better seal around the top/lid and placing the thing on a rubber mat, but the design is such that only so much can be done.
2273163
Very poor design.  Takes a lot of force to press the buttons.  The entire front piece of the device would stick in the depressed position and required me to tap it pretty hard on the side to get it to return to unpressed position. Only worked sporadically even then. Sometimes the Hue scene assigned to a button was initiated by a push, most of the time, nothing.

I don't know why they insisted on using a kinetic switch to generate the power to operate the wireless communications for this device instead of simply installing a simple battery.  Who cares if you have to replace/recharge the battery once in a while?  This kinetic switch ruins the whole device.  This thing would have been great if it simply had an easy to use switch that communicated with the Hue hub device and turned the scenes on and off.  Instead, the designers got too clever for their own good and produced a terrible product.  I try out new products all the time and am usually forgiving of flaws in the first iteration, but this product is terrible and I don't see how they could improve it without blowing it up and starting all over again.
38843
Due to a poor design this headset causes discomfort, and eventually pain, when worn.

Not to mention I've been recently experiencing problems with the left left speaker, which cuts off when the cord is jolted (to get it working again one must 'fiddle' with the cord around the "controller" then, once working again, handle gently).

In conclusion, the bad design of this product causes not only problems, but discomfort and pain as well. My advice: spend a little bit more to ensure you get a better quality product.
I am personally disappointed because I usually have a good experience with Logitech products.
728443
Poor design - wobbles while in use, traps air. Poor workmanship - no-slip strips to long for step.
273875
Poor design, the side arms break quickly and the unit is worthless.  Spend a few extra bucks and get a better design.  I bought two and neither lasted more than 10 days before they were thrown away.
1374334
Am extremely mechanically inclined.  This physically doesn't fit together, had to return.