If you landed here directly, check out the first seven posts of this series, The complete industrial designer:
Stage 1: Research & observation
Stage 2: Sketching
Stage 3: Form & proportion
Stage 4: CMF
Stage 5: CAD & surfacing
Stage 6: Prototyping & model-making
Stage 7: Hardware UX
Unlike what many IDs think of a constraint, manufacturing literacy actually gives you leverage. The person who knows how a thing is made is the person whose opinion about how it looks stops being just an opinion.
This last stage is a long one so don't try to go through this in one sitting.
Stage 7 ended by saying you're about to hand this to your design engineering counterpart, so that's really what this last stage is. Enough manufacturing to have the conversation, then the package you have to hand over, then where you stop and where they start, and then what comes back to you for approval before any of it ships. But first, what does the handover look like.
ID hand over documents
By now there are multiple stages of work sitting in different files. The simplest way to know if the work done so far is organised and documented well. If you hand these over to the next person or another ID, they should be able to continue building without calling you. Here's what you'd need:
A document with the brief of the project, contents from stage 1 and the requirement list under the brief.
A Google Sheet with field research & benchmarking. A couple of ways to organise this document like putting observations in each row, and have columns for what happened, how many people out of how many, and where. Measurements, with columns for the object, the dimension, and the value, so tap clearance and fridge shelf height and bag pocket and neck opening. Bottles studied, with a row per competitor and columns for volume, diameter, height, cap height, weight empty, weight full.
A tight presentation deck with the brief, four to five considered direction, why this one, the black fill silhouettes at full and half and empty, the competitor line-up at matched height, real photos of the prototype with things that worked, the final form from six angles, and the CMF.
A PDF or deck as your exploration archive. Every sketch from stage 2, categorised, with the part count written on each.
A similar PDF or deck as your CMF exploration archive. Inspirations you've looked at, stories each tell, practical trial developments, to the selected ones.
A Google Sheet with master dimensions. This will be shared between ID and DE. Put name of component, value, tolerance, unit number, owner (as ID or DE or shared), reason, purpose of the component, and last updated as columns. Things like body diameter, waist diameter, total height, fill line, neck height, cap height, sleeve top, etc. will go here.
A CAD file, native plus a STEP. This is the final clean file with named parts. Include a short README explaining what each parameter controls, in plain words.
A PDF of the technical drawing set with the neck and cap in section at twice the size, showing the thread, the seal and how much it squashes, the latch, and a thumb drawn on the button for scale. The waist in section view with wall thickness. And an exploded cap with every part numbered and annotated.
A CMF specification document PDF. This one should have:
Material with grade per part, supplier, and an alternative. Colour as L*a*b* values from a physical master sample, with a ΔE tolerance stated per part. Finish specification per part too with SPI grade on the tool for the clear body. Gloss units with a tolerance for the parts, all textures as a Mold-Tech or VDI catalogue number. The hard coating specified. Lightning standard for every colour check (D65 + 3000K warm light). Tests required for colour retention (accent colour fading out).
Two copies of the physical samples. There ought to be three in each set that are signed and dated, so master and lightest acceptable and darkest acceptable. Similarly seal and other rubber parts samples with specified shore values, and a sleeve (or something else) equivalent sample too.
A folder of renders including, but not limited to, full, half, and empty bottles. Put real colours under daylight and under 3000K, also side by side for comparison. One with a hand in shot for scale. And one alongside Larq and Muji and Stanley at matched scale.
A Google Sheet with the list of hardware UX issues to fix. This is the output of stage 7.
One more thing to do while the hand over is taking place is to ask at least three vendors on what would they change about this design to make it easier to make. The answers are sometimes more valuable than the typical DFM route for both ID and DE.
What you'll (should) learn after you hand it over
If you're an aspiring to become a 'complete' ID, the handover is not the finish line. Everything in that handover folder now goes to your design engineering counterpart, and over the next few months you'll sit in rooms where people use words you don't know yet and make calls that slowly would change your design. But even if everything that follows is for someone else to own, you can understand this enough to ask the right questions.
We learned earlier that to get the bottle made, we'd go ahead with either injection blow moulding, stretch blow moulding, or injection moulding. Each of them have different output types for the bottle body with different wall thickness, weights, and seams. Go and learn all three so you can understand which method is the team going ahead with and why. You'll learn about parting line and you'll be able to push through because now you know how to match aesthetics with moulding type.
You'll also learn about steel and why that matters to get the output you had rendered, visualised. From steel hardness to weld lines to flow lines and why they come, what's required to avoid them in areas you want to avoid them. You'll learn how to read mould-flow report along the way. You'll learn how critical the milestone of steel cutting is. You'll learn the phrase steel-safe and why removing steel is easy and adding is nightmare. You'll learn that the part quality actually the function of how good the tool is.
You'll get exposure of tolerances; not just of individual parts but when they stack up. How each part has different geometry and run differently in tooling and how they stack up in assembly to become slightly loose or tighter, and a hundred such things.
And you'll learn that packaging is yours to own too, and not procurement's. The first impression of taking out the product from the box is user experience and you own that experience. Own, not just design. And you'll learn all the details in packaging too.
Then you'll come back, again and again, for colour and finish sign-off on real moulded parts under real light.
Remember, the handover moves the work forward but doesn't end your involvement in it. None of this makes you an engineer either, and it shouldn't. It makes you the ID whose opinions are getting stronger, tighter, and complete.
Recommended reads
I've referred to a lot of reading material, processes, approaches to do this series of complete industrial designer. Will you actually become a complete industrial designer? No. But, my attempt here is to pick a simple, familiar product that where you can exercise the muscle of observation, ideation, documentation, all the way through production. And in doing so, you'll become a far more competent Industrial designer. And becoming a competent ID is a pre-requisite for the roles that IDs will morph into in the coming years.
These are the resources I keep handy and refer to frequently:
CMF course - Raw notes I'd taken from a Domestika course
I'll also recommend you reading through the writings here. If you found this useful, share it ahead.
All the best.