Reddit reviews Inkbird Digital Cycle Timer Switch Preset Scale IDT E2RH Relay Tact NPN PNP Input Dual Function Register 100-240V Programmable Time Setting

I've got extra adderall in my system that I need to burn off, so you're going to get the benefit of a decade of mechanical engineering and prototyping work in defense, consumer products, aerospace and medical. Not all of this will apply to a senior design project, but it is my thought process when prototyping.

1. Capture the voice of the customer (what EXACTLY does it have to do). Write it down. Verify it with the customer. Make sure you know exactly what success looks like. Translate this into the minimum viable prototype to achieve this success. Example of tradeoffs you can make at the prototyping stage: If it's a small portable device, but to go from phase 1 to phase 2 you don't have time to miniaturize the power supply, microcontroller, and secure batteries, the first prototype will be on a power and data tether from a laptop. If it's something mechanical that eventually has to weigh less than X, it can be fabricated quick and dirty as a proof of concept before you start adding expensive lightness.
   
   
2. Minimize innovation. Read that again. Minimize innovation. Don't be innovate anywhere you don't have to. Reuse whatever you can from the next closest thing, and only invent something new or do something unique/custom/cool/fun where you are adding unique value. Don't assume it is cheaper or easier or better to make something yourself instead of applying an industry-standard solution unless you already comprehensively know the pros and cons of the next best competitors and have a good idea why they made the tradeoffs that they did.
   
   
3. Try to only have one miracle per prototype. If you are inventing a new remote control something-or-other, don't try to test the controls and the mechanics and the motors and the battery all at once. Take an existing product and switch the motors out, put it back to stock and work the bugs out of the control system, then do the control system AND the motors, and once ALL of that works, try the control system, motors, and your new chassis all together, since you will be able to pinpoint what is going wrong much easier.
   
   
4. Know what questions you are trying to answer when you are going to consult with the customer. If you have a design decision, build prototypes far enough to be able to show them the difference (do you want it to work with a twist knob or a pull tab? How does this feel in your hand compared to this? Is this easy enough to adjust or does it need more friction?). Know before you talk to the customer what questions you want to ask.
   
   
5. Rapid prototyping can make beautiful parts...if you get good at sanding, bondo, and spray paint. It is worth a day of prep time to make your final version parts look nice. Anything that needs threaded fittings should get pressed and glued-in brass inserts, threads into plastic in prototype parts will strip exactly when you don't want them to and ruin your day.
   
   
6. For any actual fabrication, it will take twice as long and cost three times as much as you think it will right now. Always order a spare of anything with a lead time of more than 20% of your total project timeline if you can afford to, and if you can't afford to, think hard about if you should buy it anyway because when it breaks, not only will you be buying a new one, you will be expediting it. Don't be afraid to buy something that is 50% of what you want to make and throw away half of it, it's probably cheaper in the long run and the process of stripping down something similar to what you want to build might spark some ideas.
   
   
7. Get an account on McMasterCarr for anything physical like bolts, valves, fittings, bearings, etc. Get an account on Protocam for anything you need made of plastic--upload your parts to them, fill out a quick form, and they will give you quotes on whether they can make it, out of what material, and with which combination of machining or additive manufacturing (3d-printing). McMaster and Protocam can get you parts quicker than anybody else. Get a Misumi catalog. They are expensive but they are the industry standard for one-off fabrication of benches, tables, test rigs, etc for a reason--they are precise, modular, and durable.
   
   
8. If you want to add any electronics to your project, try to find something that is close enough and make it work--example, do not program your own temperature or flow control modules, just buy them. There are a whole lot of processes that can be controlled 'good enough' by a $30 PID controller off of Amazon. or clever use of limit switches and timer relays. If you can't do that, find someone who is good with Arduino and then google aggressively for similar projects (whatever it is, it has been done before) and steal as much of their code as you can get away with and still have it do what you want it to do. You will almost never need anything more than an Arduino unless you are a very CS-heavy group in which case you should know what you want to use instead.
   
   If you have specific or more focused questions around your project, I can reply to PM's if you'd like.

I thought about getting into building them but shipping them would be a huge pain. I used Amazon for the 395nm LEDs, a 120v to 12v converter from eBay and I just switched to this timer:

https://www.amazon.com/Inkbird-Digital-Switch-110-220V-IDT-E2RH/dp/B008KV65MS

These are perfect. There's also a 4-cycle one, but this one does the job. Two intervals, each programmable.

http://www.amazon.co.uk/gp/product/B008KV65MS?psc=1&redirect=true&ref_=oh_aui_search_detailpage

The same thing is available on US Amazon.

Relay Timer: https://www.amazon.com/Inkbird-Digital-Switch-110-220V-IDT-E2RH/dp/B008KV65MS

Pressure Switch: https://www.coleparmer.com/i/dwyer-cxa-s3-water-pump-pressure-switch-nc-range-35-150-psig-2-4-10-3-bar/6806346

Pump: https://www.kleen-ritecorp.com/p-58407-aquatec-58-flc-220-pump-with-220-psi-pressure-swich-internal-bypass-12-motor-leads-115-vac.aspx

Solenoid valve: https://www.amazon.com/gp/product/B007N0J98E/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1