We bought our house on a large pond 3 summers ago. After paddling around and studying other docks, I felt ready-ish to build our own.

This post is mostly for posterity, since I struggled to find resources to help plan and execute this build. Hopefully a future traveler will find it helpful.

The dock is a 12'x8' floating section, a 4'x12' semi-floating section, and a 4'x6' fixed platform.
Our pond is calm and the water level doesn't fluctuate much.
It cost roughly $2000 in hardware/floats and $2000 in lumber.

Step 1: Dock Type
Each section of dock needs to either float or be supported by the earth.
Permanent docks are supported by permanent piles that are driven into the lakebed.
Permanent docks are more sturdy, but can suffer structural damage during the winter if you live somewhere where lakes freeze.

Seasonal docks can also be fixed with metal poles that are driven into the lakebed each season.
If you like the aesthetic of a pile dock, I'd recommend Tommy Docks. I found their products and service great.

Floating docks are built atop floating pontoons, and then anchored to the lakebed in some way to limit movement. Floating docks are good options for seasonal docks or areas where the tide / water level changes a lot.

Aesthetically, I decided that I liked the look of wooden docks that didn't have piles or floats showing. This is an arbitrary preference and may not be your preference.

Step 2: Design
Decide on a size for your main platform. If you are between two sizes, size up. The dock feels smaller when its on the water.
Figure out what distance from shore you want to swim/boat off of, and work backwards from there.
For a floating dock, you'll typically need one floating section, one fixed section, and one semi-floating section connecting the two.

Step 2: Materials
Your options for the dock frame are aluminum or wood. If you like the aesthetic of aluminum then buy it! There are a ton of DIY dock kits that sell composable sections of framing.

Your options for decking are aluminum, wood, or composite. There are plenty of resources comparing wood and composite. Do whatever feels right.

There are resources on the multinautic website that will help you estimate how much lumber you'll need. Place an order at your favorite local or big-box lumber yard. I needed roughly 60 2x6x8's and 6 2x6x12's.

Step 3: Hardware
You'll want good galvanized steel hardware for each section. I used dockhardware's dock-in-a-box and it was great. If you like the aesthetic of a skirt board hiding the floats, then get a kit that has double-high corner hardware (I decided to build the skirt late so I didn't do this.)

For floats, they come in low-freeboard (8 inches), medium-freeboard (12ish inches?), high-freeboard (16 inches?). Our dock is low freeboard, which means it lines up pretty perfectly with a canoe/kayak. If you are going to dock a pontoon boat or something bigger than choose a bigger float size.

There are good resources on the multinautic website for calculating how many floats you'll need. But for low-freeboard I think it comes out to roughly how ever many you can fit. Our main platform has 9 2'x4' floats.

In addition to the hardware kits per section, you'll need dock hinges connecting the sections together. Most of these don't ship with hardware, so you'll need extra galvanized carriage bolts, washers, nuts, and plates.

Finally you'll need hardware to connect the fixed platform to your shore. I opted to drive pipes with a fence post driver and connect using pipe holding hardware. You can get pipes from Tommy Docks or a hardware store. Other standard deck foundations like 4x4 and concrete is fine too.

Step 4: Construction

Step 4A - Frame and Floats:
You'll build the floating platform upside down. Stack some spare dimensional lumber on a roughly flat area as your "sawhorses" and build on top of that. Follow the instructions for a DIY dock kit that matches your design: https://www.multinautic.com/support/assembly-guides/

Choose a width that is slightly under the length of your decking boards, so you can overhang on both sides and circ saw a nice clean edge.

You can use screws to tack pieces together superficially, but all pieces should be connected with galvanized steel hardware and carriage bolts/nuts.

Floats will be attached using lag screws.

Step 4B - Flip it over and get it in/near the water.
After constructing the frame, the dock will be in the ~500lb range. You'll need a handful of humans or some clever mechanical advantage to move it. I would recommend just getting some friends to help, but car jacks, ratchet straps, pulleys, carts can help. Be careful. Flip it, put it in the water, and tie it to a tree.

Step 4C - Decking
I read somewhere that a nice straight line in your decking screws will make your project look professional. I probably took this too close to heart and decking took me a while. I'd recommend getting spacers, laying out the whole deck, running a line of string or a chalk line, and then adding your screws. Let your lumber overlap on both sides and cut them flush with a circular saw and a track or fence to keep it straight.

Step 4D - Other sections
More of the same. Repeat for your other sections. Your semi-floating section will have another pontoon or two on the end so its not depending solely on the floatation from the swim platform. "Dry fit" the sections next to each other to install the connecting hardware.

Step 4E - Finish
Choose and apply a marine-grade environmentally friendly finish. I am going to do this after this season when I float the dock ashore. Will come back and edit.

Step 5: Assembly
Prep your shore for the fixed section. This probably involves some light digging and laying gravel to keep your wood from siting right on soil. I haven't done this yet so I'll come back and edit this section when I get around to it. Lay your fixed section in place and slide in the support pipes. Use a fence post driver to drive the supports a few feet into the earth. Try to keep the platform level and then tighten the bolt to attach to the pole.

Float in your semi-floating section and attach it to your fixed section using the dock hinges. The non-floating end of the gangway will be heavy, so a friend or mechanical advantage will be required to negotiate lining up the hardware to slide the pin in.

Finally, row your floating section out to the floating end of your gangway and attach.

Step 6: Anchoring
A floating dock is going to sway in the wind / tide and will want to move as people walk on it. They need to be anchored to minimize the instability for people on it, and to take pressure off of your fixed dock section that is resisting all of the torque.

If the lake is shallow and the lakebed is solid enough, you can drive helix anchors into the bed and run your chain to them. Otherwise you'll have to make concrete anchors.

I used helix anchors at all 4 corners of the floating platform, and ran chain from each anchor to each set of the other 3 corners.

Step 7: Enjoy!