Beginner
≈ 5 h 30 minSuggested range3 h 30 min – 8 h
Official LEGO® image · © LEGO Group and/or the respective rights holders. Source: LEGO Italy ↗
Technic · SET 42123
McLaren Senna GTR™
The blue Senna GTR displays mechanisms and aerodynamics in a compact Technic model.
- Pieces
- 830
- Release year
- 2021
- Theme
- Technic
- Set number
- 42123
- LEGO recommended age
- 10+
- LEGO retail price · Italy
- 49.99 €
Retired from the LEGO Italy catalogue when checked on 23 October 2026. Availability can change. Check the store for the latest information.
Retail price reported by the LEGO source for the stated market. Check the store for current price and availability; this does not establish the launch price. LEGO ↗ · Reference checked on 23 October 2026
Official English name verified at: LEGO English catalogue ↗ · Checked on 24 October 2026.
TIME TO BUILD
How long does it take to build McLaren Senna GTR™?
A starting point for planning your build. Times for each experience level are editorial estimates, not measurements submitted by HowLongToBuild users.
Editorial model estimate · no verified measured building time
Intermediate
≈ 3 h 45 minSuggested range2 h 15 min – 5 h 30 minExperienced
≈ 2 h 45 minSuggested range1 h 45 min – 4 hBased on one person building the set for the first time, following the original instructions and using numbered bags where supplied. Includes normal piece-finding and minor adjustments; excludes long breaks, filming, dismantling and modifications. Sources may use different methods. This range is neither a statistical interval nor a limit: your build may take less or more time.
How we estimate times · sources and method
Engine, steering and precisely fitted doors and livery. The three central durations are model-specific editorial assessments. Planning ranges extend approximately from 65% to 145%, rounded to quarter-hours; they are not measured experience-level averages or guaranteed limits.
Sources do not always specify the builder’s experience. The three experience bands are our editorial assessment, based on the complexity of the set and individual accounts where available.
- LEGO Italy · McLaren Senna GTR™ ↗
This source documents the model’s features and components, not a timed build. No sufficiently verifiable individual building-time report has been identified for this set.
- LEGO building instructions · McLaren Senna GTR™ ↗
Set-specific instructions checked against the set number, piece count and year. The duration is an editorial assessment based on piece count, construction type, mechanisms and detail.
Checked: 23 ottobre 2026 · Method v1.0 · Limited reports; not a statistical average.
BUILT BY THE COMMUNITY
Yours could be the first building time.
0 reviewed solo building times.
No solo building times have been reviewed yet. You can still find editorial estimates under Suggested times.
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How much display space does it need?
Model or component measured by LEGO
- Height
- ≈ 9 cm
- Width
- ≈ 12 cm
- Depth / length
- ≈ 32 cm
These measurements refer to the model or component in the original specification below. Other builds, poses or arrangements may need additional space.
Check your shelf space
Which model was measured? · original Italian specification
Il modello misura 9 cm di altezza, 32 cm di lunghezza e 12 cmdi larghezza.Approximate assembled-model measurements, not packaging dimensions. Allow extra room for handling, moving parts and the display stand. The comparison uses the measured model’s overall footprint, allows a 90° rotation and does not assess stability or shelf load. Source LEGO ↗ · 2026-10-29
BEYOND THE BRICKS
Did you know?
Inside the set
A moving V8
The engine recreates piston movement.
LEGO sourceDihedral doors
Doors open upwards beside the large wing.
LEGO sourceBeyond the set
The stories, places and inventions behind your build.
Seventy-five examples
The real Senna GTR was produced in seventy-five track-only examples.
Read the full story
Senna GTR was offered as seventy-five track-only cars, distinct from the road-legal Senna. Senna Brands’ 2020 account describes 825 HP and availability to road-car customers. The GTR designation identifies a particular purpose within vehicles sharing the driver’s name.
A São Paulo presentation
Senna Brands reported São Paulo’s February 2020 presentation of Latin America’s sole example, with the Fundação Lia Maria Aguiar choir.
Read the full story
São Paulo’s 18 February 2020 presentation of Latin America’s sole Senna GTR brought together McLaren, Senna Brands and Fundação Lia Maria Aguiar. The foundation’s choir sang Tema da Vitória and unveiled the car, connecting the ceremony with Ayrton’s televised victories and an educational community.
Expanded stories updated on 29 October 2026
Written by HowLongToBuild · Sources are linked with each story · Checked on 23 October 2026. Historical facts and story details refer to the context described.
THE COMMUNITY’S EXPERIENCE
What was it like to build?
Three separate scores from 1 to 10. For difficulty, 1 means very easy and 10 means very difficult.
No approved ratings yet. Scores are never generated by this site or inferred from the recommended age.
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Building tips from the community
Specific steps, useful checks and sticking points. Contributions appear after moderation, in their original language. Do not upload instruction pages or personal contact details.
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Sign in to contributeSET THE MOOD
A soundtrack for your build
· Selected for the subject and atmosphere
Guitar, bass and a relaxed groove accompany travelling scenes and everyday places. This adds movement without turning the session into an action sequence.
OUR PICK
The Universe Smiles Upon You
Khruangbin
Rhythmic and livelyEditorial suggestions, not official soundtracks for the set. External services may require an account or subscription; editions and availability can vary by country. Suggest another soundtrack →
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YOUR NEXT BUILD
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Sets from the same theme or with similar suggested building times. The ranges shown are for intermediate builders.
Official LEGO® image · © LEGO Group and/or the respective rights holders. Source: LEGO Italy ↗
Official LEGO® image · © LEGO Group and/or the respective rights holders. Source: LEGO Italy ↗
Official LEGO® image · © LEGO Group and/or the respective rights holders. Source: LEGO Italy ↗