Lego or Foamcore Mold Boxes vs Shop Flasks | RUUIPON

Lego bricks and foamcore boards can dam a one-off craft pour on a kitchen table. They are not a production flask. A shop box has to hold a vacuum-degassed platinum shot without whistling at the seams, sit square so pour height is a millimetre spec, and come apart without tearing keys. Foamcore soaks, Lego leaks at every stud, and both fight a food-cavity SOP because you cannot document the dam as part of a 177.2600 article. We would not quote MOQ 20 skins off a Lego flask photo. Send a STEP or let us build the box; USD $50 when CAD scope applies.

RUUIPON pours in leak-tight flasks in Bao'an since 2018. Prototype 3–7 business days after CAD lock. MOQ 20 pieces per design. [email protected] · +86 135 3006 2969. Steel/LSR *parts*: wydsilicone.com.

Does not apply when you are damming clay for a brush-on glove that will never see a box (that's a dam-material page), when the "box" is already a CNC jacket, or when you want us to vacuum-cast food. Chocolate wells stay atmospheric, dry, no grease, no tin.

What a production flask actually has to do

Leak-tight at pour and at vacuum. If we degas in the cup and pour into a whistling Lego wall, you reintroduce the air we just pulled. Foamcore corners wick platinum and then delaminate.

Known interior. Volume calc is box minus master plus waste. A studded Lego interior is not a rectangle you can trust. Foamcore thickness varies by brand. We weigh shots from a measured flask.

Square pour height. Loaded-tray sag of about 0.5–1.5 mm is a jacket problem; a tilted foamcore wall is a wedge-shaped block you then fight on the bandsaw.

Release from the skin. Production flasks are soaped, taped, or made from materials that let the block drop. Lego keys into the rubber along every stud. You spend the tear-strength budget on the box, not on the logo.

Run Structure Decision before you pick a box at all: flat back → open-back tray, maybe no box, a board. Else split / plug. Large wet dump → mother mold. A Lego castle around a figurine is not that decision.

Hobby dams we will not multiply to MOQ 20

We will look at a Lego-pour prototype as *geometry evidence* if you also send dimensions. We will not copy the stud texture into a food tray. We will not spec tin because the hobby kit was tin and the Lego was handy.

ISO 3302-1 M2 is a drawing class on the dump, not a brick-count.

flowchart TD
  A[Master needs a dam] --> B{Production SKU, vacuum, food, or MOQ 20?}
  B -->|yes| C[Shop flask or CAD box — not Lego / foamcore]
  B -->|hobby one-off| D[Lego or foamcore may dam a gravity pour]
  D --> E{Will you vacuum the pour in the box?}
  E -->|yes| F[Stop — those dams whistle]
  E -->|no gravity| G[Accept leak and stud print risk]
  C --> H[Witness pour, then MOQ 20]

The photo that would prove the flask: interior dimensions on a scale, seam detail, master seated, no stud print. A colorful brick wall around a figurine is the hobby photo.

Typical shop values

Caption: Typical shop values.

Volume math falls apart on a studded interior

Box minus master plus waste only works if the interior is a known envelope. Lego studs add unmeasured rubber and then print a grid into the block you have to trim. Foamcore bows when the platinum head is high, so the last corner shorts and you get a foam face on a food logo. We mix a waste factor of about 10–20% on small pours in a *measured* flask, mix 1:1 or 10:1 by weight, and we would not mix "exactly the Lego calculator number."

A production flask also gives you a repeatable pour height when you recast. Hobby dams get rebuilt by eye; keys walk. If you need twenty identical skins, the fixture has to be a fixture.

Loaded chocolate sheets still care about sag 0.5–1.5 mm on the tray, which is a jacket/board spec, not a brick-wall spec. Don't stack Lego under a food tray and call it a mother mold.

Worked example (anonymized)

Buyer sent a foamcore box around a 3D-printed badge, studs of hot glue at the corners, asked for 24 production trays including a chocolate SKU. We used the photo as outline only, $50 CAD to model a clean open-back, poured platinum ~25A in a shop flask, food path named, craft resin version as a second skin. Foamcore was scrap. MOQ 20 per design. We did not vacuum inside their foamcore.

Shipping a hobby flask is not packing a tool

Foamcore crushes in a carton. Lego sheds bricks on the tarmac. If you need us to see your dam, photograph interior millimetres with a ruler and ship the master only. Export packing for production skins is a crate and humidity conversation on another page. Don't tape a brick wall into a FedEx box and call it the mold.

One procurement mix-up

"The YouTube mold box is the tool." The box is a fixture. The tool is the RTV skin (and jacket if needed). Tooling charge is not ownership of a brick wall, and it is not a promise we store Lego.

We would not recommend

We would not recommend Lego flasks for vacuum pours.

We would not recommend foamcore for food cavities.

We would not recommend multiplying a leaking hobby dam to MOQ 20.

We would not recommend greasing studs so they "release better" into chocolate.

What to ask when you're buying

• Gravity hobby pour or production vacuum flask?
• Interior dimensions, or do we CAD the box ($50 if scope applies)?
• Food vs craft — two skins if both?
• Open-back tray vs buried block?
• Who owns the flask at reorder?

RFQ copy-pack

Send to [email protected] · +86 135 3006 2969 · Xinhe Blvd, Shajing, Bao'an.

RUUIPON flask vs hobby-box RFQ Photo of current dam if any Dump: food / PU / plaster / other Need vacuum on the pour in the box? yes / no Interior mm if known Qty: witness / MOQ 20 CAD: locked / $50 3D for clean flask + cavity

Matched next step: send envelope dimensions, not a brick photo as the tool. We build flasks that hold a platinum shot. We will not pour chocolate in Lego. Prototype 3–7 business days after CAD lock. MOQ 20 per design.

Related: how to build a mold box, silicone volume calculator, custom mold quote, contact.

FAQ

Can I ship you a Lego-boxed master to copy? You can ship the master. We'll unbox it. The bricks stay yours. We pour in a flask.

Does foamcore count as a jacket? No. A jacket is a mother behind a glove. Foamcore is a dam. Wet dumps need a real mother.

Will a tighter Lego wall let me skip vacuum? No. Cup vacuum still happens on the rubber. A tight hobby wall still isn't a measured flask.

Can I use the same foamcore box for soap and chocolate? We would not share food and soap cabinets. Recast food in platinum, dry well, no tin.

If CAD is locked, do I still pay $50 to replace foamcore with a flask? Usually no — flask is our fixture. $50 applies when cavity geometry is still open.