When prototyping or creating circuits for your projects, once components are soldered to a PCB, there is a limit to how reusable it is in other circuits due to damage de-soldering. That's where D1M BLOCKS come in. They are a casing/stacking system for the Wemos D1 Mini line of boards and shields. The stacking for reuse is a part of the design spec for these boards and shields. The casings provide some protection, labeling and an attachment groove to ensure the correct pin stacking. The wiki for the Wemos boards and shields is here.

There is also a visual program editor for the blocks based on Blockly: D1M BLOCKLY. This instructable is used in combination with the D1M BLOCK pages on Thingiverse. Each page states the pin length on the headers and the solder jig to use.

Step 1: Material and Tools

There is now a full "Bill of Materials" linked on the individual (standard shield) thingiverse pages that partner this page.

The Wemos D1 Mini SOC or Shield
3D printed Base and Lid for the D1M BLOCK (on the Thingiverse page that linked to this page)
Indentifier Label and possibly Pinout Label (from the Thingiverse page)
2 off 8 pin Needle Female Pin Header Strip (length specified on Thingiverse page)
A set of D1M BLOCK - Install Jigs
Hot glue gun and hot glue sticks
Strong Cyanoachrylate Adhesive (preferably brush on)
3D Printer or 3D Printer Service

Step 2: Soldering the Header Pins (using the PIN JIG)

Depending on which D1M BLOCK you are assembling, you may need to use the PIN JIG or the SOCKET JIG. The type is clearly detailed in the Thingiverse page that referred you to this page. There is a video above that runs through the solder process for the PIN JIG.

Feed the header pins through bottom of the board (TX right-left) and into the solder jig.
Press the pins down onto a hard flat surface.
Press the board down firmly onto the jig.
Solder the 4 corner pins.
Reheat and re position board/pins if needed (board or pins not aligned or plumb).
Solder the rest of the pins

Step 3: Soldering the Header Pins (using the SOCKET JIG)

Depending on which D1M BLOCK you are assembling, you may need to use the PIN JIG or the SOCKET JIG. The type is clearly detailed in the Thingiverse page that referred you to this page. There is a video above that runs through the solder process for the SOCKET JIG.

Feed the header pins through bottom of the board (TX top-left on the top side).
Feed jig over plastic header and level both surfaces.
Turn jig and assembly over and firmly press header onto a hard flat surface.
Press the board down firmly onto the jig.
Solder the 4 corner pins using minimal solder (just temporary alignment of pins).
Reheat and re position board/pins if needed (board or pins not aligned or plumb).
Remove the jig.
Place assembly with pins down onto flat surface.
Solder the rest of the pins and the 4 corners on the other side of board.

Step 4: Gluing the Component to the Base

Once the pins have been soldered the remaining steps are the same for all D1M BLOCKS.

With the base casing bottom surface ponting down, place the soldered assembly plastic header through the holes in the base; the (TX pin will be on side with the central groove).
Place the hot glue jig under the base with the plastic headers placed through its grooves.
Sit the hot glue jig on a firm flat surface and carefully push the PCB down until the plastic headers hit the surface; this should have the pins positioned correctly.
When using the hot glue keep it away from the header pins and at least 2mm from where the lid will be positioned.
Apply glue to all 4 corners of the PCB ensuring contact with the base walls; allow seepage to both sides of the PCB if possible.
On some PCBs where the board ends close to the pins, dob a large amount of glue onto the base to the height of the PCB; when this cools apply more glue on the top of the PCB bridging to the lower glue.

Step 5: Gluing the Lid to the Base

Ensure the pins are free of glue and the top 2mm of the base is free of hot glue.
Pre-fit the lid (dry run) making sure no print artifacts are in the way.
Take appropriate precautions when using the Cyanoachrylate adhesive.
Apply Cyanoachrylate to the bottom corners of the lid ensuring coverage of the adjacent ridge.
Quickly fit the lid to the base; clamping shut the corners if possible.
After the lid is dry manually bend each pin so it is central in the void if necessary.

Step 6: Adding the Adhesive Labels

Apply pinout label on underside of base, with RST pin on side with groove.
Apply identifier label on flat non-grooved side, with the pins void being the top of the label.
Press labels down firmly, with a flat tool if needed.